Airbag control unit with part number 3Q0959655BM

What does the airbag control unit 3Q0959655BM do?

The airbag control unit 3Q0959655BM is the central control unit of the restraint system (SRS) of Volkswagen. It evaluates the signals from the crash sensors and decides in an accident which airbags and seatbelt pretensioners are triggered. It monitors the system continuously and reports faults via the airbag warning light. After a crash it stores crash data and locks itself.

The signals are evaluated in fractions of a second. To do so it processes the values from the connected sensors.

Why does the control unit 3Q0959655BM fail?

The most common cause is crash data that stays stored in the unit after an accident, even if no airbag was deployed; a normal diagnostic tool cannot erase it. Other causes are aged components, cold solder joints, moisture and corrosion, and voltage spikes.

In detail, these further causes are possible:

• Aged electronic components
• Cold solder joints
• Moisture and corrosion on plug connections
• Voltage spikes, for example from a weak battery or a jump start

Airbag24 erases the crash data during the repair.

How can you tell that the 3Q0959655BM is defective?

A defect shows up as the airbag warning light, as an error message in the instrument cluster, as a lack of contact with the diagnostic tool, or as a fault memory that cannot be cleared. In an emergency the airbags and seatbelt pretensioners may then not deploy.

• Airbag warning light in the instrument cluster, permanently or intermittently
• Error message in the instrument cluster
• Diagnostic tool receives no connection to the control unit
• Fault memory cannot be cleared

Have such signs checked promptly, because the light shows the state of the system.

Which vehicles is the 3Q0959655BM fitted in?

The 3Q0959655BM is fitted in these vehicles: Volkswagen Crafter SY (from 2017) and SZ (from 2017).

The following list shows the vehicles stored for this part number.

• Volkswagen Crafter SY (from 2017)
• Volkswagen Crafter SZ (from 2017)

Comparing the part number from the removed unit with this page only confirms that you have the right unit in front of you. The fault memory, however, must be read out before you remove the unit, because only it shows whether the control unit itself is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 3Q0959655CL.

How does the repair of the 3Q0959655BM work?

First comes reading out the fault memory with the enclosed log. Then you disconnect the battery; only after that do you remove the control unit. Next you create the repair order online and pack the unit well for sending.

On the test bench Airbag24 examines the control unit, and defective components are repaired. Stored crash data is erased by Airbag24 afterwards, followed by a function test. Processing usually takes 3–4 working days.

Our repairs come with 2 years' statutory liability for defects. The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.

How does the control unit 3Q0959655BM get to Airbag24?

You hand in the unit as a parcel. Alternatively, you book a UPS collection for an extra charge. After the repair Airbag24 brings it back to you by UPS.

Put the printed repair order into the parcel and pack the unit shock-proof.