Airbag control unit with part number 31690549100U

What does the airbag control unit 31690549100U do?

The airbag control unit 31690549100U coordinates the restraint system (SRS) of BMW. In a crash it evaluates the measured values from the sensors and determines within milliseconds which airbags and which seatbelt pretensioners trigger. If an accident occurs, the unit stores crash data and locks itself.

The control unit is in continuous operation, even if you notice nothing of it. As soon as it detects a fault in the system, it shows it via the airbag warning light.

Only the repair lifts the lock.

Why does the control unit 31690549100U fail?

Stored crash data are the most common cause, and this applies even if no airbag has deployed. Other causes of failure are aged components, cold solder joints, corrosion on connectors, moisture and voltage spikes.

Stored crash data cannot be erased with an ordinary diagnostic tool, and the other causes of failure can only be narrowed down case by case.

During repair at Airbag24, stored crash data are removed.

How can you tell that the 31690549100U is defective?

Typical signs are an airbag warning light that burns permanently or intermittently, an error message in the instrument cluster, and a diagnostic tool without a connection to the control unit. A fault memory that cannot be cleared also points to the defect.

These signs occur as follows:

• The airbag warning light in the instrument cluster burns permanently or intermittently.
• An error message appears in the instrument cluster.
• The diagnostic tool does not establish a connection to the control unit.
• The fault memory cannot be cleared.

In an emergency, airbags and seatbelt pretensioners may possibly fail to trigger. That is why you should take the warning light seriously, because it shows the defect as soon as it is present.

Which vehicles is the 31690549100U fitted in?

The unit 31690549100U is fitted in these vehicles: BMW 3 Series E46 (1998-2007). Matching the overview shows whether your vehicle is covered.

The vehicles in the overview:

• BMW 3 Series E46 (1998-2007)

The label of the removed unit shows a part number; compare it with this page. That way you make sure you have the right unit. Reading out the fault memory before removal clarifies whether the unit is defective or a connector or cable is causing the fault.

For the same vehicles, we also repair control units with the part numbers 285001368, 285001458, 285001681, 31693323800A, 6577-6905491, 6577-6912755.

How does the repair of the 31690549100U work?

At the start is reading out the fault memory; attach its log to the parcel. Only then disconnect the battery and remove the control unit. Create the repair order online, then pack the unit and send it in. Airbag24 needs 3–4 working days for checking, repairing and testing.

You carry out the removal as the last step. Before that you take care of the fault memory and the battery, because the order serves safety.

On the test bench Airbag24 examines the unit, repairs defective components and concludes with a function test. Stored crash data are erased in the process. Afterwards the unit returns to you.

The 3–4 working days refer to checking, repairing and testing at Airbag24 and do not include the steps on the vehicle or the shipping.

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 31690549100U get to Airbag24?

You ship the unit as a parcel, or you book a UPS collection for an extra charge. The return after the repair is likewise by UPS.

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