Airbag control unit with part number 89170-50M31

What does the airbag control unit 89170-50M31 do?

For Lexus, the airbag control unit 89170-50M31 handles the evaluation of the restraint system. The crash sensors supply their readings to the unit, which decides within milliseconds in an emergency which airbags and seatbelt pretensioners are triggered. It monitors the system continuously and reports faults via the airbag warning light.

The control unit constantly checks whether all components are fully connected and whether the signals remain plausible.

After an accident, the unit stores crash data and locks itself. This storage is part of the unit's function and must be taken into account during diagnosis.

Why does the control unit 89170-50M31 fail?

The most common cause is crash data from an earlier accident, even if no airbag was triggered; standard reading devices do not restore it to its initial state. Added to this are ageing components, dry solder joints, moisture in plug connectors, corrosion and voltage spikes.

Ageing electronic components lose their function over time.

Dry solder joints create only an unreliable contact.

Moisture and corrosion on plug connections impair signal transmission. Voltage spikes, for example from a weak battery or a jump start, can also damage the unit.

How can you tell that the 89170-50M31 is defective?

The airbag warning light in the instrument cluster lights up permanently or flickers intermittently. In addition, a fault message appears, the diagnostic tool cannot find the control unit, and the fault memory remains even after reading out. In that case, airbags and seatbelt pretensioners may fail to deploy in an emergency.

The light is the clearest sign the system gives. If it stays on, a prompt check is the right course.

A diagnostic tool that cannot get through to the control unit indicates a fault whose cause must still be established.

Which vehicles is the 89170-50M31 fitted in?

The control unit 89170-50M31 is fitted in these vehicles: Lexus LS XF50 (from 2018). If in doubt, compare with the label.

These vehicles are recorded for the part number:

• Lexus LS XF50 (from 2018)

Compare the label of the removed unit with the details here first, so that you have the correct unit in front of you. Also have the fault memory read out before removal. Only this log shows whether the control unit is defective or whether a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 89170-50K81, 89170-50K83, 89170-50L00, 89170-50L03, 89170-53790, 89170-53820.

How does the repair of the 89170-50M31 work?

First have the fault memory read out and place the log in the parcel; disconnect the battery before you remove the control unit. Then create the repair order on the internet and send the packed unit in. Airbag24 examines it on the test bench, repairs defective components, clears crash data and tests the function.

The sequence is mandatory for safety reasons, because working on the airbag system otherwise carries risks.

The processing time at Airbag24 for testing, repair and the function test is usually 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 89170-50M31 get to Airbag24?

A parcel, or a UPS collection booked for an extra charge, brings the unit to Airbag24. The return after the repair is likewise made by UPS.

Insert the printed repair order into the parcel and choose shock-proof packaging.