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A systematic approach to BMW remote central locking repair

Make: BMW

Model: E61 ( – ) | ALL / E91 ( – ) | ALL

Symptoms: A common symptom presented itself with the remote central locking failing from the remote fob

“When it comes to the BMW E61 and its remote central locking mechanism, the frustration and inconvenience caused by failure can’t be ignored,” states Simon Tyrrell , BMW Master Technician for Opus IVS.

“My job is to support workshops to discover efficiency with their diagnosis and repairs on complex vehicle systems. From my experience, diagnosing and fixing issues, such as that with the BMW remote central locking failure, requires a systematic approach, combining technical knowledge and expertise to get to the root of the problem, efficiently.

With the BMW E61 remote central locking failure, we discussed and provided step-by-step guidance to ensure our customer got the correct diagnosis the first time, and of course, had the repair steps lined up so the repair was carried out quickly.”

Possible Causes:

1. The wiring is broken going through boot loom 2. The CAS module has failed
3. The Diversity Unit has failed or is full of water.

Repair Steps:

“With possible root causes understood, our customer now has a starting point to begin the following checks, and related repair steps,” states Simon.

1. Check that the central locking works by pressing button in the vehicle

2. Access to the Diversity Unit which is under the boot spoiler

With access to the Diversity Unit, check for water ingress in and around the unit.

3. Check the 12-volt supply to the Diversity Module (E61 pin 1) (E91 pin 6)

If you do not have 12v on (E61 pin 1) (E91 pin 6) we must suspect broken wires in the right-hand hinge loom. All wiring repairs will involve disconnecting the right-hand loom and pulling it in through to the boot area via the Right-hand roof speaker.

Note – It is believed that the roof speaker is only for the E61 model, so it is worth stating that. The E61 has a boot loom repair kit available for the left and right looms.

4. Check the signal line at the Diversity Module with the connector plugged in (E61 pin 2) (E91 pin 3)

With a Multimeter check for 4.8v approx. on that line then press the unlock or lock button on the remote fob. The multimeter voltage should now fluctuate to show the message is being sent to the CAS module. You could use an LED test probe and watch for the LED flashing when the unlock and lock buttons are pressed. If there is a signal fluctuation or LED flash, it suggests the Diversity Unit is working.

Note – this can also be scoped, see Figure 1.

Figure 1

5. Now gain access to the CAS and check for the same signal change at pin 33. If there is a signal fluctuation or LED flash at pin 33 it suggests the Diversity Unit and the signal line are ok and the CAS is the issue.

If you have 4.8v at (E61 pin 2) (E91 pin 3) but do not get a signal change it could be the Key or Diversity Unit at fault. Please repeat signal testing using a Donor key, as long as it is the same style of key it will generate a signal fluctuation/LED flash. If with the Donor key you get a signal fluctuation or LED flash then the customer will need a new key. If not, then the Diversity Unit is at fault.

If you do not have 4.8v present on (E61 pin 2) (E91 pin 3) it indicates a faulty/broken wire. Please check continuity between pin 33 at CAS to (E61 pin 2) (E91 pin 3).

Opus IVS’ customers have direct access to direct
repair guidance from their team of OEM trained Master Technicians, providing brand-specific diagnostic support to technicians and workshop owners all over the world.

Customers can quickly request support from the IVS 360 team directly from their DrivePro device as well as access training to gain the most from their diagnostic tools.

To find out more about Opus IVS solutions, garages can get in touch for a complementary product evaluation at their workshop. Email

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