Airbag control unit with part number 89170-78091

What does the airbag control unit 89170-78091 do?

The 89170-78091 is the central airbag control unit of the SRS system of Lexus. It processes the sensor signals, selects the appropriate airbags and seatbelt pretensioners within milliseconds of a collision, and checks the entire system without interruption. If it detects a fault, it reports it via the airbag warning light.

While driving, the checks run continuously in the background. After an accident the unit stores crash data and locks itself.

Why does the control unit 89170-78091 fail?

Stored crash data from an accident is the most common cause at the 89170-78091, even if no airbag has triggered. Aged electronic components, cold solder joints, moisture and corrosion at plug connections also play a part, as do voltage spikes from weak batteries or jump starts.

This data remains in the memory because a normal diagnostic tool cannot erase it. Only during the repair does Airbag24 remove it.

Aged components, cold solder joints and corrosion on plugs are among the known weak points.

How can you tell that the 89170-78091 is defective?

A defect at the 89170-78091 shows as an airbag warning light in the instrument cluster that lights up permanently or intermittently, together with an error message in the same display. A diagnostic tool then finds no connection to the control unit, and the fault memory cannot be cleared. In an emergency, airbags and seatbelt pretensioners may then not trigger.

The light reports the fault directly. A sign like this calls for a check, however well the vehicle otherwise runs.

Which vehicles is the 89170-78091 fitted in?

The 89170-78091 is fitted in these vehicles: Lexus NX AZ20 (from 2021). The assignment applies to this part number.

The following vehicles are stored for this part number:

• Lexus NX AZ20 (from 2021)

Comparing the part number on the label of the removed unit with this page shows only whether it is the same unit, nothing more. Have the fault memory read out first, because this result alone shows whether the control unit itself is defective or whether a plug or a cable is the cause.

For the same vehicles, we also repair control units with the part numbers 89170-F6010.

How does the repair of the 89170-78091 work?

Your steps begin with reading out the fault memory, whose log you attach, and disconnecting the battery. Then you remove the 89170-78091, create a repair order online and send the unit in well packed. Airbag24 needs 3–4 working days in total for the check, the repair and the function test.

Airbag24 checks the unit on the test bench, replaces defective components and deletes the stored crash data. A function test follows.

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 89170-78091 get to Airbag24?

You send the 89170-78091 as a parcel or book a UPS collection for an extra charge. After the repair Airbag24 sends the unit back to you by UPS.

Include the printed repair order and pack the control unit shock-resistant.