ECU issues and how to fix them

The ECU is truly a wonderful piece of engineering. Not only does it contain a lot of functionality, but to reliably operate in a harsh environment with very variable conditions is a big achievement. However, the reliability still leaves something to be desired every now and then. Why can’t they solve these weaknesses?

It might be useful to start with some elaboration about the technology that’s used inside an ECU. Of course, the basis is formed by a processor, memory and a PCB (Printed Circuit Board), but there is really much more to tell.

The PCB

We’ll start with the PCB itself: The well-known green printed circuit board, made out of fibreglass and epoxy resin, is still used regularly, but the arrival of ceramic material has made some manufacturers switch. Ceramic printed circuit boards can conduct and dissipate heat much better and are made
of much finer and better structured material, which allows for very high precision manufacturing. This also has its advantages for printed circuit board design, as it also makes possible very small and complicated 3D structures. Car manufacturers are very eager to take advantage of these characteristics, as any form of space and weight saving is welcomed with open arms. We therefore expect to see the use of ceramic material in ECUs even more in the near future.

Ceramic printed circuit boards are mostly glued to an aluminium base plate with a heat-conducting paste. This gives the circuit board its firmness and lets the heat (generated

by active components) dissipate quickly. Deformation and vibration therefore occur way less with ceramic printed circuit boards. It also prevents possible consequential damage due to these deformities. Cracks in solid connections are therefore also relatively rare. So, all-in-all, the use of ceramic material really has huge advantages. We even dare to say that the now somewhat older green printed circuit board is partly to blame for the varying reliability of some current ECUs.

Components on, and inside, the PCB

It should come as no surprise that this difference in printed circuit boards also results in a different use of components. A conventional printed circuit board has a coarser structure in comparison to the ceramic variant. The components themselves are therefore logically somewhat more “robust”
in design. Most contact points are therefore large enough to be seen without a microscope. You would therefore think that these components are also more reliable than the smaller fragile components on a ceramic printed circuit board, but strangely enough, this theory does not seem to hold true in reality. The larger components still regularly fail. Could low manufacturing costs play a role in this?

Fortunately, with suitable (solder) equipment and sufficient skill, much is possible in repairing connections and replacing components on these conventional printed circuit boards, even if the contact points are located beneath the component, as is the case with processors such as BGAs. You’ll need special high-end equipment that can heat locally with extreme precision, but it’s doable for real experts.

An ECU with a modern ceramic printed circuit board.

So, if something fails on a conventional printed circuit board, repair is possible in many cases. However, with components that are used on a ceramic printed circuit board, it suddenly becomes a lot more difficult. Because the overall design can be made smaller and more complex, it also becomes necessary to use smaller components. Fortunately, heat dissipation is not a huge problem due to the use of the ceramic material, even if these components are embedded. However, as soon as these delicate electronics fail, repair is not that easy. The components are difficult, if not impossible, to reach and they’ll damage quickly. In addition, the joints are often so small that they cannot be repaired without a microscope and some highly advanced equipment. It’s not impossible, but you must keep asking yourself in each individual case whether this is still economically justifiable.

Joint by wire

Speaking of joints, due to the compact and complex design of a ceramic PCB, solder joints aren’t the obvious choice. Manufacturers often resort to wire connections, which can be microscopic. For example, the wire connections that run from the PCB to the ECU connectors are clearly visible, but the hundreds of gold wires connecting the square purple component in the centre of the PCB are only 50 microns thick and therefore almost invisible to the naked eye.

Note: These small gold wires are an excellent example to explain why you should never touch components with your fingers: The probability of pressing these gold wires together and thus cause a short circuit is very high.

Let’s be honest: These wire connections are clearly the weak spot of modern ECUs. They cannot withstand the continuous vibrations and temperature fluctuations for several years, circumstances that are common under the bonnet. This is mainly why a layer of silicone gel is applied, which should protect against this. However, this silicone gel does not prevent us from regularly encountering ECUs with faulty wire connections. And in our opinion, the chosen position of the ECU is also partly to blame. For example, on top of an intake manifold is not the most tactical position for a sensitive piece of technology such as an ECU. Yet some cars actually have the ECU placed right there!

Unlike the components themselves, the wire connections on a ceramic printed circuit board are often easily repairable. That is, if you have the right (often expensive) equipment and use the correct methods. The thin aluminium wires cannot be soldered reliably, even if in theory there would be space for this option. But if soldering isn’t the solution, how do you get these wire connections reattached to a contact point?

Ultrasonic wire bonding

A possible solution is to opt for ultrasonic wire bonding, as ACtronics have also done. As the name suggests, ultrasonic vibrations are used (frequency: 60 kHz) to make two metals (in this case the contact surface and the bonding wire) flow into each other. We won’t go into too much detail, but we can tell you that this way of bonding takes place quickly, accurately and without the addition of heat. The technique is therefore particularly suitable for use around delicate components.

In addition, the new joint is particularly strong: the result is comparable to a welded joint.

In short…

The shift to ceramic material has really benefited the ECU, as the older green circuit board has its drawbacks. Components appear to last longer due to better heat dissipation; solid connections suffer less from distortion and vibration and the design can be made much smaller, lighter and more complex. However, there is also a downside: wire connections. The ECU itself is by no means always to blame for the failure of these connections, but we cannot deny that this is clearly a weak spot. Fortunately, there are also companies such as ACtronics that have thoroughly studied this problem and can therefore provide a qualitative solution.

www.actronics.co.uk

At ACtronics, a company that focuses on remanufacturing of electronic automotive components, they also use local heating to replace components. The machine has been programmed entirely in-house, creating a fast and precise solution for replacing BGAs. Programming this equipment does require a lot of specific knowledge and the equipment is very expensive. It is therefore not expected that other companies will follow quickly in these developments.

The Multec HSFI 2.X – A regular customer at ACtronics

“Multec? Aren’t they those ECUs (Engine Control Units) that are commonly used in Vauxhalls?”

We’re not sure if it’s a good or a bad sign, but almost every car connoisseur we speak to, knows that many Vauxhalls are equipped with a Multec ECU. Why do so many people know the name Multec? Are these ECUs really that bad? Multecs are indeed malfunctioning a lot, but this is due to several causes. It is short-sighted to put the blame entirely on the ECU itself.

Lesson 1 – when using car-electronics, always ensure the utmost protection against moisture, temperature fluctuations and vibration. Maybe Vauxhall is a little at fault in this matter – mounting an ECU right on top of the inlet manifold simply doesn’t provide the best possible environment.

What’s causing the main malfunctions?

So, the ECU is operating in a hazardous environment full of vibrations and big differences in temperature. What could possibly go wrong? Several connections on the PCB (Printed Circuit Board) tend to tear or break and it’s no surprise for us to find these defects in every Multec we get hold of. So, it actually doesn’t matter which faults we find inside the ECUs, we always check all connections directly after every diagnosis. It’s really rare to have all connections on the PCB in perfect order. Almost every Multec will therefore continue to undergo our full remanufacturing process.

It’s probably no surprise that all these defects are causing so much trouble. The complaints we find on incoming Multec ECUs are also diverse. Below, we’ve made a short list of the most common complaints:

• Car doesn’t start, fuel pump isn’t activated • Car doesn’t start, no injection
• Ignition fails on one or more cylinders
• Fluctuating RPM at idle

• Absolutely no throttle response • Faults in EGR
• No communication to CAN
• Cooling fan isn’t activated

Remanufacturing: The process

We can’t stress enough that ACtronics doesn’t repair defects, but remanufactures products. We know for a fact that these ECU’s are highly sensitive and we want to be absolutely sure a remanufactured ECU will have the quality equal to, or better than, OE (Original Equipment). We therefore not only repair all the complaints we encounter, but we also put each ECU through the complete remanufacturing process.

In this process, the protective gel will first be removed professionally. Once all components are completely unprotected, we can begin with the removal of all existing bonding wires. This is a very delicate process, but this isn’t an issue thanks to our many years of experience. Once this second step is completed, all new bonding wires will be attached to the PCB using highly sophisticated equipment. The method we use is called ‘ultrasonic bonding’. The equipment is fully programmed and set up by our engineers and because of this we can also perform a pull test on the freshly installed bonding wires. This way we know for sure every new attachment is strong enough to withstand vibrations and fluctuations in temperatures. The newly made connections are even stronger than the original ones.

Once the bonding process is complete, it is time for the final test. This test is necessary to establish if all the functions are working properly. Our testing facility also gives us the ability to perform an endurance test, in which the temperature actually rises in the ECU. You can really feel the ECU getting hot while performing this test. After this testing period, a special high specification gel will be applied in order to properly protect the PCB. Finally, we will close the ECU with a new (self-developed) cap.

If the ECU still isn’t working properly after this entire process is complete, we will proceed using much more specific methods. There are many possibilities in the field of diagnosing and solving problems.

To find out more, visit www.actronics.co.uk, or email your query to info@actronics.co.uk.

FUN FACT…

The Multec HSFI ECUs are also used in cars with diesel engines. There is one malfunction that’s really standing out in these particular cases: Fault code P0251 (Injection Pump Fuel Metering Control “A” Malfunction). If you ever experience this fault code on a Multec ECU that controls a diesel engine, please send in both the ECU and EDU (Engine Diesel Unit). In most cases, it’s the EDU that’s causing this fault code, not the ECU itself.

Preparing for winter: plugs and coils

With Bosch Aftermarket reporting that ignition failure is more prevalent in cold weather conditions, you might wish to prepare now for an increase in demand. Rob Marshall gives an overview of spark plugs and coils, investigates how they fail, describes routine checks and examines low-cost tools to help you with dismantling and diagnosis.

Should you maintain classic British cars, in particular, the quality of pattern ignition components is so poor that you may wish to consider offering an upgrade that replaces the contact breaker points and condenser with a sealed hall sensor and transistor unit. Pictured is a maintenance-free PowerSpark unit, fitted to a Lucas 45D4 distributor, which ensures a constant dwell angle and more powerful sparks at higher engine speeds.

Despite the huge advances that have been made in engine electronics, the spark ignition internal combustion engine remains reliant on a high voltage circuit to generate the several thousands of volts necessary to jump-across the spark plug electrodes’ gap. The vast majority of modern ignition systems employ a coil to generate this high voltage (or High Tension – HT ) output from a low voltage (or Low Tension – LT ) input, employing Faraday’s Law for readers that have either good memories, or an O-level/GCSE Physics textbook to hand. Essentially, once power is cut to a primary coil of wire within the coil assembly, the resultant magnetic field collapses and high voltage is subsequently generated within another internal coil winding. The spark plug is connected either directly to the coil unit(s), or via a series of high voltage flexible HT leads, or both. Naturally, the type of coil fitted depends on the car model being worked upon, the attributes of each type will be examined in a future issue. Even so, a mechanical distributor might be employed on some older cars, made until the early 2000s, despite lacking ‘Old-Skool’ vacuum-advance timing mechanisms and contact breaker points that are present on most historic vehicles.

Rendering contact breaker points obsolete, a transistor within the engine ECU supplies the LT to the coil(s). Naturally, this is controlled by a microprocessor that considers the many other signals received by other sensors fitted to the running gear. Among many benefits, modern transistorised ignition systems can ensure an optimum dwell angle, an advantage of which is that the coil is supplied with LT voltage for long enough to ensure optimum spark strength. The HT voltage tended to reduce gradually on older cars with contact breaker points and is one reason why the driver would notice a significant improvement in engine performance after a service had been completed, which is not always that obvious today.

While modern spark plug electrodes should pre-gapped for your engine application, it is worth double- checking them with a dedicated
wire gauge, in case the plugs have been dropped in transit. Never
place pressure on the centre electrode. Pictured is a NGK Iridium IX spark plug, which offers superior performance, as well as a longer lifespan. Yet, some engines require precious metal spark plugs, so do not downgrade them.

AVOIDING CORNER CUTTING

Even so, a modern ignition system is not immune to neglect and premature ignition coil failure tends to be the result of neither making the appropriate checks at service time, nor the owner heeding maintenance schedules. Mobiletron advises that poor fuel economy, stalling, back-firing and difficult starting are typical symptoms of coil issues. SMPE reports that the main checks tend to be restricted to visual inspections that might not be stated specifically in maintenance literature, which comprise checking the insulating gaiters and the LT electrical connections. More detailed advice is included within our earlier feature, www.autotechnician.co.uk/servicing-be-a- bright-spark.

“High resistance in the ignition system will prematurely kill any coil,” reports Morten Hansgaard Jensen, Product Specialist of Ignition at the Bosch Aftermarket Division. He adds: “While a resultant misfire might cause unburnt fuel to overheat the catalytic converter, the coil has not had a chance to release the energy that it has ready for the spark plug. Instead, it is transferred as heat within the coil that will shorten its life.”

When inspecting coils, look for corrosion, cracks in the coil body and rubber insulators, as well as evidence of ‘tracking’ (which may be displayed as a dark line on the white spark plug ceramic insulator). Be suspicious if you find any oil/water contamination within the engine’s spark plug tubes, these issues can cause misfires and premature coil failure.

Apart from internal short and high resistance, Denso adds that defective cables, low battery power, vibration and mechanical damage also reduce coil service life.

Walker Products says that other factors within the cylinder, such as a faulty fuel injector producing an incorrect spray pattern, or even low compression, can vary the voltage demand on the coil. This means that a spark plug can be used as a combustion chamber sensor. Coil-on plug systems that employ Delphi’s Ion Sense Technology, for example, can monitor conductivity at the spark plug electrodes to detect misfires, knock and even fuel mixture/quality. The resultant signals are then sent to the engine ECU. While skilled technicians have used oscilloscopes to diagnose poor running conditions for years, Ion Sense enhances and simplifies this technique, by providing real-time feedback directly to the ECU, while the engine is running.

Rubber gaiters from either coils, or HT leads, can fuse to the spark plugs. Peter Wallace, Senior Business Line Manager at Motaquip, says that a suitable grease should combine decent lubrication/insulation properties and have an operating temperature of between -40 to +200 degrees Celsius. Its use will make fitting/separation easier and the insulation layer should prevent arcing that guards against subsequent misfires and component damage.

When servicing, however, Tim Howes, Deputy General Manager of the Supply Chain & Technical Service at NGK Spark Plugs (UK), advises that, “If the coil is mounted directly on the plug, the coil would need to be removed to gain access, giving the opportunity to visually check for perishing/contamination of the rubber parts, plus corrosion, cracks and evidence of current leakage ‘tracking’. It is important to use the correct specialist tools when removing and refitting ignition coils, in order to prevent damage to the insulating materials, circuit boards, windings, connectors, etc.”

Denso adds that, should an ignition coil be identified as defective, the root cause should be determined, to avoid the replacement part failing prematurely as well. Naturally, the vehicle manufacturer’s ignition system instructions should always be referred to in the first instance but disconnect the negative (-) battery terminal and wait at least 90 seconds before removing the coil. Naturally, corner cutting extends to replacement parts. NGK reports that sub-standard coils tend to be cheaper but their inadequacies are not obvious by inspecting the outside, because the quality of the internal windings and potting materials tend to be where savings are made. Lower HT voltage and even internal short-circuiting can ensue. These inadequacies can result in an engine that is more reluctant to start, increased misfiring frequency, raised exhaust emissions and increases the likelihood of damage to the catalytic converter and engine. Both SMPE and ACtronics also advise that low-quality coils can cause severe damage to the engine ECU, due to the incorrect fly-back voltages received.

Yet, ELTA advises that technicians should check the spark plugs first, because they tend to cause suspected coil-related issues, before embarking on an exhaustive diagnosis procedure.

Pay specific attention to any tightening instructions and note the sealing design
at the thread base. Bosch Aftermarket, for example, recommends that if you encounter
a spark plug with
solid washer for a GDI application, you should always use a torque wrench to ensure correct installation. Image supplied courtesy of NGK.

SPARK PLUGS: THE BUSINESS END

It is easy to forget just how much of a hard life a typical spark plug endures. Even at engine idling speeds, each one must ignite the fuel mixture eight times a second, be expected to withstand huge temperature variations in milliseconds, because combustion heat is followed immediately by a cooling effect from air being drawn in through the inlet valve(s), and resist forces that can be the equivalent of fifty times the force of gravity. Should any replacements be fitted that do not combine high mechanical strength, with effective insulators that can contain at least 30,000 volts, misfires could be the least of the problems encountered. The plug could disintegrate, causing catastrophic physical damage to the combustion chamber.

While NGK told us that it has witnessed plugs being mis-sold as premium precious-metal types, the arrest and subsequent charging of an online trader in May, who sold counterfeit spark plugs that could have damaged engines had they been fitted, proves that you should prioritise not only trusted brands but also proven suppliers.

Yet, incorrect fitting can also damage even the best plugs. Antoaneta Spiridon, Motaquip’s Business Line Manager – Spark Plugs, advises that plug threads should not be lubricated, because this reduces the friction at the thread faces, risking overtightening. Distortion of the plug’s metal shell can result, which interrupts the heat transfer path within the plug, causing the electrodes to overheat. These ‘hot spots’ make pre-ignition more of a threat, which is something that you do not wish to promote in certain GDI engines that are prone to Low Speed Pre Ignition. Follow any fitting instructions carefully with GDI engines, so that the ground electrode is positioned correctly, relative to the fuel injector. The use of either a dial, or torque wrench, is essential; use a short as possible extension bar and keep it straight. Tilting the extension bar/socket may exert excessive side pressure on the spark plug and crack the brittle insulator. Incidentally, periodic adjustment of the spark plug gap between services tends to be unnecessary on modern cars, although it is recommended on cars that run on gas.

Never downgrade specifications, either. While older cars may benefit from being fitted with a precious-metal spark plug, due to the more focussed spark offering a more efficient burn, they are mandatory on some newer and high-performance engines. Fitting a more conventional nickel-alloy type risks prejudicing engine efficiency, which is likely to promote an illuminated MIL. Just like a spark plug that is worn-out, fitting replacements of an incorrect specification risks placing extra strain on the ignition coil, something that can then have ramifications for the entire engine management system.

USEFUL DIAGNOSTIC TOOLS

As separating ignition components by hand might damage them, ask your supplier about the range of tools that are available to reduce the risk. Pictured is Laser’s spark plug gaiter lead removal tool (part no 2719), the use of which should save workshop time. It is also worth investing in coil removal tools, especially for pencil-type designs.

Simple high voltage diagnostic tools can pay for themselves the first time that they are used. Pictured is Laser’s HT lead spark tester (part no 2780), which can be used to deduce whether a spark plug, or its voltage supply is at fault.

You can also evaluate whether, or not, the coil is supplying a strong-enough spark to the spark plug, by adjusting the electrode distance with Laser’s 5655 adjustable spark tester.

 

Giving ECU’s a new lease of life

Engine Control Units, or ECUs, are integral to any modern vehicle. They form the brain of the engine and are what essentially controls it, ‘talking to’ the other control units on the vehicle. 

As the ECU is constantly operating, processing signals and data, it is inevitable that the small unit is likely to become faulty at some point in its life. But this doesn’t mean that it is the end of its life cycle when it does develop a fault. 

ECU’s in general are relatively hard to damage, due to most vehicles having other modules and fuses in place that are designed to fail first before the ECU does. However, when such an important control module does fail, a new one from a dealer can potentially write the car off, ending the life cycle of the vehicle many years before it needs to be. 

Replacing the ECU for a new one could resolve the issues on the car; however, it condemns a unit that can potentially be remanufactured, increasing the amount of automotive environmental waste unnecessarily and increasing the cost for the end customer. 

In this article, we will be talking about the EDC16C34 ECU, which can be found on Ford, Mazda, Fiat and PSA Group vehicles, but in this instance, the ECU will be from a Peugeot 206. 

Some of the common faults to occur on the vehicle that relate to the EDC16C34 can be: 

• 5-volt circuit faults

• EGR faults or basic settings not able to set

• Loss of injector signals/injector fault codes. 

These faults could have developed for various reasons, such as short circuits in the wiring, a spike of voltage or excess heat on the unit, due to its location within the engine bay. If the ECU has failed, the vehicle could develop a faulty injector signal, fail to start or suffer complete power loss. 

Here, we will talk about the faults found on the 5-volt circuit. This circuit feeds a range of sensors, such as the throttle position sensor, MAP sensor, Camshaft sensor and Crank Sensor, with the ECU forming part of the 5-volt circuit. 

The ECU ‘simply’ has two wires; one that serves as the ground and the other is the 12-volt circuit, which feeds into the ECU. The ECU then converts the 12V feed into 5V, which returns out of the ECU, feeding the sensors its 5V. If the 5-volt connection within the ECU fails, it breaks the circuit, which will then lead to inaccurate readings from all the sensors and will display fault codes relating to the sensors. This could lead to sensors being replaced unnecessarily. However, the damage that can be caused on the ECU can range from blown capacitors and resistors to damaged tracks and processors, that will all need replacing by specialist machinery and processes developed by ACtronics over 15 years. 

BESPOKE TESTING 

ECU technology is advancing at an incredible rate and because of how advanced it has become; we have our own bespoke- built testing machine. The Vision 6 is able to simulate the ECU being on the vehicle, however, to do this and to not remove the immobiliser from the ECU, we would require the standard immobiliser set from the vehicle. 

As we are talking about the Peugeot 206, we would require the key, transponder ring and the Body System Interface (BSI) to fully test the ECU. When the key is inserted into the ignition barrel, an analogue signal is sent from the transponder ring to the COM 2000 unit, which translates the analogue to a VAN Bus signal to the BSI, which translates to a CAN Bus signal. This is sent to the ECU and will then allow the vehicle to start. However, the COM 2000 and transponder ring are universal – we have golden units here to use when testing. 

When we simulate the ECU on our Vison 6, we can adjust the correct sensor input signals that would be sent to the ECU, so that we are able to see the ECU activating like it would be on the vehicle. 

By using the immobiliser components, we are able to test the unit for complex and specific faults, if the right diagnosis is done on the vehicle. 

As part of the testing procedures, the ECU will also be opened so the technician is able to visually see the Printed Circuit Board (PCB) for potential physical damage to the components on the PCB. ACtronics believes in conducting a thorough, professional test on every unit. 

If a fault has been confirmed on the ECU, it would enter the remanufacture process, where the ECU can be further inspected and the faulty components removed. Removing the minute components can be tricky and requires specialist developed techniques, which allows us to remove the components from the PCB without causing any further damage. 

If there is too much heat supplied directly onto the PCB when removing the faulty components, it could damage the unit permanently. With our specialist machinery and developed techniques, we can control the temperature of the heat applied to within 0.5°C, for example. 

Being able to adjust and control our techniques for individual units allows our technicians to provide the
best remanufacturing solutions for our customers. Once a remanufacture has been completed on the unit, end of line testing is conducted and our two-year warranty is then applied. 

ACtronics has an extensive range, including: ABS-unit, ECU, instrument clusters, Throttle body, TCU and many other electronic components. The electronic components are completely renewed at ACtronics and not repaired with a temporary solution. For example, all the wires that connect to the circuit board are provided with double bounds (wires), something that does not happen with an original product. This extends the lifetime of a product and provides a good alternative to a new product. 

www.actronics.co.uk 

 

Cam & crankshaft sensor fitting tips

Camshaft sensors often fail due to damage from oil contamination, so you need to ensure any oil leaks are addressed before replacing the sensor. After removing the old sensor, oil the ‘O’ ring of the new sensor, ready for installation. 

The correct positioning of the new sensor is critical as camshaft sensors often feature slotted mounting holes and/or locating pins. Ensure any locating pins are correctly seated before fully slotting into place. Failure to do so can shear off the locating pin, causing misalignment and incorrect readings. Finally, reconnect wiring and reset the ECU if required. 

Some cam/crankshaft sensors are particularly difficult to replace, usually due to awkward fitting locations within the engine bay, camshaft sensor EE0018 being a good example. Elta Automotive says this has the highest return rate under warranty, but when tested the diagnosis usually rejects the claim as it is not faulty, but damaged due to a fitting error. The sensor is located in a particularly tricky position and is often returned with the locating lug sheared off, probably as a result of securing the sensor into place without correct alignment. The slight misalignment of the sensor has a dramatic effect on its performance, as can be seen in the accompanying scope readings. 

VXPRO products from Elta Automotive are tested to ensure they operate within the manufacturer’s original parameters. Technical advice for each part can be accessed via QR codes on the packaging. 

EMAIL: sales@elta.co.uk 

Servicing – be a bright spark

While ignition components have always needed a degree of maintenance, Rob Marshall looks at how modern systems, including engine management, can be affected by service neglect, incorrect replacement techniques and poor quality replacement parts.

It is surprising how many members of the public consider that classic cars are far easier to service than modern vehicles. At least modern ignition and engine management systems have negated the regular and fiddly need to set accurate contact breaker points gaps and ensure optimum dwell angles, both of which tended to be almost impossible to execute accurately in any case, when many distributor shafts possessed excessive play in their bearings…even when new. Close inspection for excessive pits on rotor arms and for evidence of ‘tracking’ on the inside of distributor caps has also been consigned to the dustbins of history in most cases, although the principles are not entirely irrelevant today, as we shall see. 

 

DON’T FORGET TO RESET 

Even so, modern cars require a different thought process and yes, diagnostic equipment is just as important to contemporary servicing, as it is for repair work. Checking for and downloading software updates, prior to writing them to the relevant ECU, is an important part of most modern car service schedules. Part of this involves not forgetting to reset the service counter. Subconsciously, the dashboard readout (most of which are at least time and mileage dependent) reassures the owner that the service has been done properly. Yet, for an increasing number of models, not resetting the indicator might fail to instruct the  oil condition monitoring system that a lubrication system had been carried-out. This can have implications for diesel particulate filter regeneration, which could cause consequent blockage – a condition that may be blamed (incorrectly) on the filter, rather than an incorrect servicing procedure. 

SERVICE NEGLECT 

Any ignition system will experience natural wear and tear but neglect will have deeper ramifications. Bosch’s aftermarket division warns that spark plugs, which are overdue for replacement, will increase their voltage demands and this accelerates wear levels on the coil(s). 

Faulty, or wet, spark plug leads can have the same effect. An engine misfire, under heavy load, can not only cause the coil to overheat (because it cannot release the energy it has built) but unburnt fuel can also enter the catalytic converter, the result of which can be the melting of its expensive, precious metal-coated structure and subsequent destruction. NGK adds that, while most spark plugs do not require their gaps checking and adjusting between replacement intervals, do not neglect the procedure, where it is specified, on older vehicles. Consider also that, unless specific LPG spark plugs are fitted, re-gapping should be added to the maintenance schedule, for a vehicle that runs on gas. Tim Howes of NGK Spark Plugs Technical Service advises that: 

“If the coil is mounted directly on the plug, the coil would need removing to gain access to the spark plug, giving the opportunity to check visually for perishing, or contamination of the rubber contents, corrosion, cracks and evidence of current leakage ‘tracking’. Use the correct specialist tools when removing and refitting ignition coils, in order to prevent damage to the insulating materials, circuit boards, windings, connectors, etc.” 

FITTING TIPS 

While most spark plugs tend to be pre-gapped for a specific application, NGK recommends that you should double-check that the gap is correct, before fitting, using a wire gauge to reduce the risk of damaging the precious metal tips of the delicate electrodes. 

Bosch adds, when installing a new spark plug to a GDI engine, you will need to pay attention to the washer design that seals the plug body against the cylinder-head. Should the spark plug possess a solid washer, rather than a crushable one, the engine requires ‘orientated ground electrode positioning’. This means the ground electrode should face away from the injector spray pattern, otherwise the combustion will be incomplete. Bosch argues that for this type of engine and spark plug design especially, a torque wrench is an essential spark plug installation tool, because it is the only way to ensure the ground electrode’s correct positioning. 

For ignition coils, Bosch Aftermarket advises that you should check for the presence of grease, or powder, within any rubber boot that comes into contact with the spark plug ceramic body, otherwise the two materials can fuse together over time. Additionally, check that the engine wire harness is fixed securely to the primary connector for each ignition coil. 

Standard Motor Products Europe (SMPE) highlights that technicians should be wary that ignition coils can be damaged easily by careless fitting. For example, certain types of rail coils, fitted to GM vehicles, can warp and crack, should their fixing bolts be tightened beyond the official 8Nm torque. 

ECU DAMAGE RISKS 

Naturally, poor servicing techniques can damage ECUs, which can be expensive and time-consuming to rectify. Christian Planting, Technical Manager at ACtronics, recommends an external means of battery support, because losing power during the software updating process can damage engine management ECUs. This is because existing data has to be erased during the updating process. Should the power be cut, while data for accessing certain components is deleted, you may not be able to communicate with the ECU, after power is restored. 

While Christian reveals that neglected spark plugs (including inappropriate gapping) do not tend to damage the ECU directly, the ECU’s internal actuators may try to compensate for poor engine running that could result in a broken driver chip. The ECU is more at risk from the fitting of low quality ignition coils, which is known to cause the ignition drivers within the ECU to fail. Christian also advises caution for any work that involves disconnecting the battery: 

“If you disconnect the battery incorrectly you might introduce voltage spikes. This can cause software to fail, because normally, the integrated circuits that contain the software are sensitive to these spikes.” 

BATTERY STATE-OF-CHARGE 

Batteries provide the opportunity to offer extra services and to upsell. Check the battery’s state-of- charge (measured in volts) and charge it externally, if required, as part of an extra service. Yet, its state-of- health (measured in amps) gives a real indication of battery condition, when you compare your figure with the Cold Crank Amps (CCA) figure stated on the battery label. You can then advise the customer whether, or not, a replacement battery will be needed before the next service is due. 

 

A problem halved – By Andy Crook

Imagine the scene – a good customer is on the phone informing you that his son’s car is on the back of a recovery truck heading to your workshop. You have never seen the car before and he wants you to take a ‘quick look’ at it. 

This is the sort of scenario that we face time and time again. The customer expectation is that the technician can diagnose the fault quickly and quote for the repair work without, or for little cost, to the customer. This may be true for mechanical work, but for electrical diagnosis on today’s modern computers on wheels, the diagnosis may take longer than the repair and therefore cost far more. 

However, the customer perception is that diagnosis is a low value commodity, after all, you just need to ‘plug in’ a tool and the car will tell you what is wrong! 

Changing this perception is made much more difficult when garages still offer their ‘diagnostic’ service for £25. I always wonder what they do for that £25. 

We have a robust process for diagnostic work and it always starts with a customer interview. This allows us to gather information about the customer and the problem, as well as explain what is required and the costs associated with the diagnosis. Essentially, it is a process where we educate the customer, then ask if they want us to diagnose the problem. 

Our diagnostic procedure then proceeds with a customer questionnaire. We have developed a form that enables any member of staff to gather some basic details. This is recorded on the job card and is the starting point for the detailed questions that are asked when the vehicle is dropped off. 

In this case, the process was a bit skewed as the owner/ regular driver wasn’t going to be with the vehicle. I proceeded to ask a number of questions: 

What is wrong with the car? “It keeps cutting out”.

How frequently? “Every 2-3 miles.”

Has it recently been refuelled? “No”. 

What work has been carried out recently? “A breakdown service has looked at it at the roadside and recovered it to a local garage”. 

Did they suggest what might be wrong? “No, they couldn’t communicate with the ECU, so they just towed it to a garage”. 

What has that garage done? “They recommended a Jaguar specialist as the ECU needs replacing or resetting, in their opinion. The specialist has managed to communicate with it and extract a code and has suggested it may be the fuel pump solenoid or the ECU,” he continued. “They have replaced a blown fuse, and this allowed the vehicle to start and run until it blew again. It has been replaced with a fuse of higher rating to get it running and help get it on the recovery vehicle. But it has blown again”. 

Distinguishing between diagnosis and the repair 

So, having established the recent repair history, we now needed to agree on a way forward. The customer was happy for us to spend up to an hour to find the fault and provide an estimate for the repair. 

This clear distinction between the diagnosis and the repair helps the customer understand why we charge a different rate for this service and why the fix is not included. It is a separate operation and therefore a separate charge on the invoice. 

This is a much different proposition to the ‘quick look’ they initially requested, but as we pointed out, it has had three separate repair agents look at it without a definitive conclusion. 

It is going to require specialist tools, knowledge and information to establish the cause of the fault, all of which is reflected in the diagnostic rate charged for this service. 

When the vehicle arrived we performed a global scan of all modules and noted the codes. 

The only code stored in the PCM did indeed relate to the Fuel Metering Valve Circuit. 

Next, we used an information system to obtain the wiring diagram relating to the fuel pressure solenoid/metering valve. Identifying the various elements of the circuit allows us to carry out the required tests more efficiently. I drew my own diagram identifying: 

Figure 1

I inserted expected values at the logical test points and formulated a test plan with the results evaluated at every measurement step. See Figure 1. 

It was clear from the customer interview the problem was an intermittent short circuit. Where the short was located is another matter entirely, we needed to come up with a test plan to prove where the short was in the circuit. 

FORMULATE A TEST PLAN

Halving is a process used to reduce the time to solve problems; it can be used to great effect during circuit diagnosis. In theory, you should be able to narrow the fault by a process of hypothesis, test and evaluation, repeat. Within five steps you should have proved the fault. 

Picking a point halfway through a circuit and applying tests, or logic, will eliminate 50% of the possible culprits if the test is robust enough. Halving the remaining 50% leaves you with 25%, halving that leaves 12.5%, halving that leaves 7.25%, and so on. 

It isn’t always possible to be so precise, but I’m sure you get the idea. If you know what result to expect anywhere in the circuit, you can measure anywhere and if the result is positive you can eliminate the circuit up to that point as the cause. 

In this case, we could rule out the ground path including the ECU from our enquiries. Shorting this side of the circuit would result in a reduction in rail pressure with the maximum current flow possible in the circuit. That’s half the components ruled out without even taking a measurement. So, we focused on the remaining half of the circuit, the wiring to the metering valve, and the valve itself. We needed to prove if the wiring or the valve was at fault, so we needed to come up with a test that would do just that. 

Figure 3

We removed the fuse and replaced the wiring to the valve with a fused link of the correct rating, connected the oscilloscope amp clamp to the fused link and grounded the control side of the valve. The oscilloscope trace shows the result, 2.2 Amps drawn by the metering valve. See Figure 3. 

We removed the ground from the metering valve and connected the plug, cleared the codes and drove it for 10 miles without any issues. This was to prove that the valve was not failing due to heat build-up. This proves the fault is in the wiring after the fuse. One test and the fault was isolated to a length of wire. We then gave the customer two options; strip the loom to locate the fault or a ‘loom overlay’. A loom overlay is simply running another wire. The customer was given estimates for both options including some advice on which way to proceed. 

Diagnostics sent into orbit – By James Dillon of Technical Topics

The advancement of technology in the motor trade is, and has been for many years, relentless. The changes over the past five years have seen the widespread proliferation of the electrification of motor transport, significant changes to diesel engine emission control systems, a shift towards engine downsizing, major advancement in direct petrol engine technology, internal engine friction reduction measures, the ‘Connected Car’ and Over-The- Air-Updates, autonomous technology and so forth. It’s a very exciting time to be involved.

Many of these changes will lead us, as technicians, having to change the way we work. We will have to adopt different working processes to repair and maintain vehicles. We will have to adopt new techniques and learn to use different tools, or similar tools in a new way, to effect diagnosis and repair. It appears that the only constant in the world of the motor vehicle technician is change itself.

One significant change in the nuts and bolts of vehicle control systems, which will definitely impact on the future day-to-day of the diagnostic technician, is the implementation, within control systems, of sensing devices that use the SENT protocol. The implementation of this technology will change the way we work without doubt, particularly during control system diagnosis, as SENT protocol sensors encode the data they gather from the vehicle (such as coolant temperature or exhaust pressure). The goals of the SENT implementation are low cost, high data rate, high accuracy sensors. It is a unidirectional (from sensor to ECU), point-to-point (no Bus) protocol. The big question is how will this technology effect the diagnostic processes of the technician?

The potential impact of this method of sensor information encoding may be better understood when imagining a typical system malfunction diagnosis. As our candidate vehicle, let’s select a ‘cooking model’ VW Golf. Let’s say it has the 1.6 Diesel engine fitted and is a 2018 Model Year. This vehicle has dropped into limp mode and the engine management warning light is on. The system has restricted performance and upon interrogation with the scan tool, the system believes that the DPF has significantly elevated levels of pressure prior to the DPF.

Figure 1: Diagnostic Process Loop

Typically, the traditional diagnostic process would involve them observing the system behaviour to confirm the fault. They would then develop a hypothesis, or theory, based on the observation experience, expertise, and resultant ‘gut-feel’ on what could be causing the observed behaviour. This hypothesis would identify suitable candidate components which require data gathering tests, such as system functions, sensors and actuators. The technician would perform these tests then analyse the data, using their expertise, in order to either prove or disprove the malfunction of the candidate components. This process repeats until the root cause is identified, see Figure 1: Diagnostic Process Loop.

In practice, the process would run the following course… The technician would validate the symptom that the customer described, perhaps through a test drive. They would reach
for the serial data stream to retrieve a diagnostic trouble code (observe system behaviour). This would help them form a hypothesis. The technician would call up relevant data PIDs (candidate selection), such as exhaust pressure actual and desired, air flow, EGR, exhaust temperature, DPF regen data, boost command and feedback and such like to gather supporting data. Any anomalies in the serial data stream would usually lead the technician towards carrying out a more detailed component test with a scope, multimeter or pressure gauge (test specification pass or fail). Analysis of this test data should lead to the problem being solved.

But what if your multimeter or oscilloscope couldn’t be used to verify the data output from a suspect sensor and you were only able to see a signal similar to a LIN data signal? How would this make you feel? And more importantly, would it change or affect the way you work? A key aspect of the diagnostic process is to test the output of the suspect component to validate its operation. Typically, this would involve both the serial data stream and the raw signal voltage. This dual measurement approach is required as many component failures can lead the controlling computer (the ECU) to set a default value in the datastream (the PID) to enable necessary calculations to be carried out so the system can continue in limited operation mode (Limp).

Figure 2: SENT component internals

The big question is that if the PID cannot be validated against a raw signal voltage comparator, how can differentiation be made upon the root cause of the issue which prompted the component validation in the first place? It is no longer possible, with components using the SENT protocol, to probe and compare. Also, it is no longer possible to use a signal simulator (or decade box) to substitute the signal and observe expected PID/data variation, as the raw signal never leaves the internals of the sensing component, so voltage simulation will not work. See Figure 2: SENT component internals.

The SENT component on the VW Golf looks a little like a normal 3-wire sensor, fitted with a 5V supply, a ground and a ‘signal’ wire (importantly, there are also 2-wire SENT devices). Upon inspection, the signal wire can be seen outputting a regular train of pulses and a typical data transfer profile. The data channel has a logic low state at < 0.5 V and a logic high state at > 4.1 V.

Figure 3: SENT waveform

The image in Figure 3 shows the data capture on the oscilloscope. I have turned on the decoding tab to look at the data contained within the SENT waveform. The image shows a protocol ID, a diagnostic message (slow channel) and the sensor data packets (fast channel). The data packets values change in line with the physical pressure changing. Detailed analysis of this data may offer an opportunity for further diagnostics.

Keeping pace with modern technology is critical to remaining competitive in fixing broken motor cars. Technicians have to keep pace with the changes and continually develop their professional competencies. The ever-changing scene of vehicle technology makes this work challenging, but also highly rewarding.

 

Oscilloscope Basics – by David Wagstaff AAE MIMI Master Technician

There will come a time when we get a car in with a fault and despite following our diagnostic procedure – with visual inspections, code reads, live data checks, voltage checks and volt drop testing – we still won’t have enough information to give us a clear answer to what the underlying cause of the problem is. This situation may occur on something as simple as a crank sensor fault or a more complex issue such as a communication network fault. This is often the point when the parts cannon gets fired, guessing the cause of the issue. Take for instance our crank sensor fault, you’ve done all the checks, so it must be the sensor that’s faulty. Crank sensors are cheap and easy to fit, so worth a guess, right? What if you fit the sensor and it still doesn’t cure the issue? What if it had been a £1,500 ECU, would you be prepared to gamble your own money on it? Or would you want to be more certain it was faulty before committing? What next?

The answer is to use an oscilloscope to test the input or output signal to prove a fault before we commit to a new part. An oscilloscope is a very useful and powerful tool but seems to
be the tool that holds most fear in the hearts of technicians.

I guess the reason for that is that the machine doesn’t give you a definitive answer in writing to a question, it requires the technician to interpret what is displayed on the screen to come to their own conclusion. To an inexperienced user this can be confusing to say the least.

Let’s start with what an oscilloscope is and what it is capable of. If I take you back to the days of your school science classes, you may remember doing an experiment where you measured the temperature of water as it was being heated. You would have measured the temperature, perhaps once each minute and plotted the results onto a graph, with time along the bottom and temperature up the side. Each of your measurements would have been plotted as a dot on the graph and when you finished you drew a line through the dots to give you a curve. That is exactly what a modern digital oscilloscope does, except where you may have been taking a sample once a minute, the oscilloscope will be taking thousands, if not millions, of voltage samples per second, plotting them all as dots and joining them with lines to display a waveform on the screen.

GETTING SET UP

There are three basic settings that as a beginner you need to worry about. The first is the voltage scale or maximum voltage that can be displayed on the screen. It should be appropriate for what you are expecting to measure. If you are trying to measure something that has a small voltage and have the scope set to show high voltage, the image will be too small to be seen clearly. Conversely, with the scope set on too low a voltage, the image will be off the top of the screen. Many automotive systems work on 12-14 Volts, so probably the most common scale to use would be the one with a maximum 20V. That is 0V at the bottom of the screen and 20V at the top. If you don’t know what you are expecting to see, start with a high voltage setting, then drop the voltage down until the image is displayed somewhere around the middle of the screen without going off the top.

The next is the time base, or how much time is shown across the screen. Different scopes may show this as either the total time across the screen, or as the time of each division across the screen. Around 50ms (milliseconds) per division or 500ms across the screen is a good place to start. Normally a good setting is within a couple of clicks of this, but if in doubt, start at a long time base (1 to 2 seconds across the screen) to check that you are actually picking up a signal, then zoom in by reducing the time to show more detail in the waveform.

The final step and one that seems to give a lot of trouble is triggers. If you run the scope without a trigger the image is drawn on the screen randomly and tends to jump around a lot from side to side making it difficult to view. A trigger is simply an event that the scope needs to see happen before it starts drawing the image. This is often a rising or failing edge, meaning that the scope needs to see the voltage rise or fall past a set voltage point. You can normally set the trigger at different points across the screen, so you see what happened leading up to the trigger point or after it. The most important part about the trigger is that it is used to stabilise the image on the screen.

So, once you have a stable image on the screen, what next? This is where it gets tricky – you must interpret what is on the screen. The easiest way to do this is to compare what is presented with a known good waveform. This could mean having to get another car that you know is good to measure, easy enough if you work for a dealer, but more difficult as an independent garage to have a similar car available. This is where I believe that PicoScope has an advantage over most of the other scopes on the market. Within the menu will be a pre-set to get you close to a good image on the screen and a waveform library of known good or bad images for you to compare with your own, to help you make a decision. Waveforms can be emailed to others with more experience to look at or posted on forums for support.

If you are going to take the next step towards fixing those tricky faults and decide to invest in an oscilloscope, then some training to get to grips with the basics is a must. Then the most important thing is not to hide it away under the bench and only get it out when the going gets tough, but to use it all the time. If you spend time looking at waveforms that are good, you’ll spot the problematic ones more easily.

A cost-effective way to compete against the VM dealer

Launched at Automechanika Birmingham last year, Delphi’s DS-FLASH Pass-Thru package provides independent garages with comprehensive ECU re- programming capability through access to vehicle manufacturer data, without the need for expensive dealer- only tools and software.

The kit is fully compliant with Vehicle Manufacturer programming requirements and comes complete with a DS-FLASH VCI, cables, a battery support unit, licence keys and a laptop PC – pre-configured for VAG Group, BMW, General Motors, Toyota and Jaguar Land Rover. Delphi provides support and training not only for the equipment, but for the registration to the VM web portal, as well as installation and use of the VM software.

Customers get a 12-month support package with the equipment, which includes a full day of training and ongoing support via a dedicated technical helpline.

In a nutshell, the DS-FLASH enables you to perform dealer-level diagnostics, download software updates including those for emission-related ECUs, update Digital Service Records and access OE technical data and service schedule information.

Autotechnician spoke to Paul Sinderberry, Delphi’s expert in Vehicle Diagnostics, Digital Service Records and J2534 pass thru, who previously ran his own garage, to get the lowdown on this piece of kit.

WHAT KIND OF BUSINESS IS THE DS-FLASH AIMED AT?

“A lot of the garages who will buy this product are workshops who are already doing a lot of diagnostics and they want to take their business to the next step. They may be doing diagnostic work for other workshops locally.”

WHAT ADVANTAGE WOULD THIS EQUIPMENT GIVE WORKSHOPS?

“One of the great things about the DS-Flash and using the OE software, is that you get very in-depth diagnostics. When you have to replace a control unit, it’s normally a trip to the dealer, and they tend to put independents to the back of the queue and wait several days to get it programmed!”

IS IT DIFFICULT TO USE?

“It’s proved a very useful tool for certain garages, it’s not for everyone. It’s quite a complicated tool to use because you’re using VM software. But then workshops have got access to our technical support helpline, so when they do get stuck, our technical guys can help set their VM accounts up.”

HOW LONG DOES IT TAKE TO REPROGRAM?

Depends on the calibration file size, the number of files and ECUs to reprogram – the latest vehicles can be as fast as a couple of minutes, vehicles with a lot of data to download can take hours. A stable high- speed connection is recommended via a hardwired PC, rather than WiFi.