Airbag control unit with part number 89170-78150

What does the airbag control unit 89170-78150 do?

The airbag control unit 89170-78150 controls the restraint system (SRS) of Lexus. It reads the signals from the crash sensors, decides in the event of an accident within a fraction of a second which airbags and seatbelt pretensioners are triggered, and monitors the entire system. After an accident it stores crash data and locks itself.

During driving the unit works continuously in the background. It checks the connected components and makes an entry in the fault memory when irregularities are found. It reports faults via the airbag warning light.

A failure of the control unit therefore affects the entire restraint system, not just individual airbags.

Why does the control unit 89170-78150 fail?

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

An accident without airbag deployment can also leave crash data behind, and many people overlook this when troubleshooting.

The other causes develop over time: solder joints fatigue, electronics age, and moisture causes contacts to corrode.

How can you tell that the 89170-78150 is defective?

The airbag warning light in the instrument cluster is on constantly or only intermittently; in addition, a fault message may appear in the instrument cluster. The diagnostic tool cannot connect to the control unit, and the fault memory cannot be cleared.

As long as the fault persists, airbags and seatbelt pretensioners may not be able to trigger in an emergency. Take this warning seriously.

The light names the fault but not the affected component. Reading out the fault memory is needed for that.

Which vehicles is the 89170-78150 fitted in?

Only the part number is decisive. The 89170-78150 is fitted in these vehicles: Lexus NX AZ20 (from 2021).

The associated vehicles are shown in this overview:

• Lexus NX AZ20 (from 2021)

Compare the part number on the label of the removed unit with this page; this way you know it is the correct unit. Have the fault memory read out before you start removal: only that result shows whether the control unit 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 89170-78150 work?

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 in well packed.

At Airbag24 the unit is examined on the test bench. Defective components are replaced, stored crash data is deleted and a functional test is carried out. Testing, repair and functional testing usually take 3–4 working days at Airbag24.

Your own unit goes back to you afterwards. 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 89170-78150 get to Airbag24?

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

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