Airbag control unit with part number 31697742702Y

What does the airbag control unit 31697742702Y do?

The airbag control unit 31697742702Y is the central unit of the restraint system (SRS) in BMW. It checks the signals from the crash sensors, decides within milliseconds in the event of an accident which airbags and seatbelt pretensioners are triggered, and monitors the system continuously. After an accident it stores crash data and locks itself.

The control unit continuously checks the components of the system and reports faults to the airbag warning light in the instrument cluster. This is how the driver learns that something is wrong.

The sensor signals are evaluated in real time before the unit decides whether to trigger.

Why does the control unit 31697742702Y fail?

The most common cause is crash data from an accident, even if no airbag has deployed. Aged components, cold solder joints, moisture and corrosion, and voltage spikes are also possible causes.

Standard diagnostic tools cannot erase this crash data. Airbag24 erases it as part of the repair.

• ageing electronic components
• cold solder joints on the circuit boards
• moisture and corrosion on plug connections
• voltage spikes, for example from a weak battery or after a jump start

The bench test establishes which cause applies in the individual case.

How can you tell that the 31697742702Y is defective?

A defect in the 31697742702Y shows up as the airbag warning light in the instrument cluster, which lights up permanently or only occasionally. A fault message in the instrument cluster, a missing connection to the diagnostic tool, or a fault memory that cannot be cleared also indicate a defect. In an emergency, airbags and seatbelt pretensioners may then fail to deploy.

The warning light is the signal that the system gives you directly. Even a brief illumination is a sign you should take seriously.

Have such a finding checked promptly. A workshop with a diagnostic tool reads out the fault memory and assesses the condition.

Which vehicles is the 31697742702Y fitted in?

The control unit 31697742702Y is used in vehicles of the make BMW. It is fitted in these vehicles: BMW 3 Series E91 Touring (2005-2008) and E91 LCI Touring (2008-2012).

The vehicles at a glance:

• BMW 3 Series E91 Touring (2005-2008)
• BMW 3 Series E91 LCI Touring (2008-2012)

Two steps will help you. First, compare the part number on the label of the unit with this page; this only confirms that you have the correct unit. Second, have the fault memory read out beforehand, because only this result shows whether the control unit itself is defective or whether a connector or a cable is the cause.

For the same vehicles, we also repair control units with the part numbers 285010062, 285010066, 285010070, 31918443202L, 65.77-9119058-01, 65.77-9122500-01.

How does the repair of the 31697742702Y work?

You first read out the fault memory and enclose the log; then you disconnect the battery and only after that remove the control unit. Afterwards you create a repair order online and send the unit in, well packed. Processing at Airbag24 usually takes 3–4 working days: Airbag24 checks the unit on the test bench, replaces defective components, erases stored crash data and carries out a function test, after which your own unit is returned to you.

This order serves your safety, so please follow it exactly.

The 3–4 working days apply only to the checking, repairing and testing at Airbag24. Reading out, removal and dispatch are not included.

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 31697742702Y get to Airbag24?

You dispatch the unit as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 sends it back to you by UPS.

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