Airbag control unit with part number 65.77-5A1FC43-01

What does the airbag control unit 65.77-5A1FC43-01 do?

The airbag control unit 65.77-5A1FC43-01 is the central control unit of the restraint system (SRS) in BMW. It evaluates the signals from the crash sensors, decides within milliseconds in an emergency whether airbags and seatbelt pretensioners are triggered, and monitors the system continuously.

If it detects a fault, it reports this via the airbag warning light in the instrument cluster. After an accident, it stores crash data and locks itself.

Monitoring runs without interruption in the background, even in everyday driving when everything seems to be in order. That is precisely why the control unit is so important for safety in the vehicle.

Why does the control unit 65.77-5A1FC43-01 fail?

The most common cause is crash data stored after an accident, even if no airbag has deployed; a standard diagnostic tool cannot delete it. Other causes are aged electronic components, cold solder joints, moisture and corrosion at connectors, and voltage spikes, for example from a weak battery or a jump start.

Crash data records the accident and remains in memory even if no external damage is visible. This becomes apparent when the fault memory is read out.

The other causes can only be reliably narrowed down on the removed unit. Airbag24 deletes the crash data during the repair and checks the other causes on the test bench.

How can you tell that the 65.77-5A1FC43-01 is defective?

The airbag warning light in the instrument cluster stays on permanently or flickers, a fault message appears in the instrument cluster, and the diagnostic tool cannot connect to the control unit. In addition, the fault memory cannot be cleared, and in this state airbags and seatbelt pretensioners may fail to deploy in an emergency.

The warning light is the most important signal the vehicle gives itself. An intermittent light deserves the same attention as one that stays on permanently.

Which vehicles is the 65.77-5A1FC43-01 fitted in?

The control unit 65.77-5A1FC43-01 is fitted in these vehicles: BMW 4 Series G23 Convertible (from 2020).

The list shows the models to which this part number is assigned.

• BMW 4 Series G23 Convertible (from 2020)

Compare the part number on the label of the removed unit with this page; then you know that it is the right unit. Also have the fault memory read out beforehand, because only this record shows whether the control unit is faulty or a connector or cable is the cause.

How does the repair of the 65.77-5A1FC43-01 work?

First have the fault memory read out and enclose the log; then disconnect the battery, and only afterwards remove the control unit. Then create a repair order online and send the unit off well packed. Processing at Airbag24 usually takes 3–4 working days.

Airbag24 checks the unit on the test bench, repairs damaged components, deletes stored crash data and carries out a function test. Afterwards, your own unit is returned to you.

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 65.77-5A1FC43-01 get to Airbag24?

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

Enclose the printed repair order in the package and pack the control unit so that it withstands knocks and arrives undamaged.