Airbag control unit with part number 89170-78020

What does the airbag control unit 89170-78020 do?

As the central unit of the restraint system (SRS) for Lexus, the airbag control unit 89170-78020 evaluates the signals from the crash sensors. In an accident, it decides within milliseconds on the triggering of airbags and seatbelt pretensioners. After an accident, it stores crash data and locks itself.

During normal operation, the unit checks the system continuously and reports faults via the airbag warning light in the instrument cluster.

The signals come together in the control unit, so a fault affects the entire restraint system.

Why does the control unit 89170-78020 fail?

The most frequent trigger on the 89170-78020 is crash data from an accident, even if no airbag has deployed, and an ordinary diagnostic tool cannot remove it. Aging electronics, cold solder joints, moisture and corrosion on connectors, and voltage spikes are also involved.

The record concerns the unit itself. Airbag24 erases the crash data during the repair.

The other causes act on the electronics themselves or on their connections. Aging components, cold solder joints and corrosion on the connectors belong here, as do moisture and voltage spikes from weak batteries or jump-starting.

Which cause applies to the individual unit is shown by the test on the test bench.

How can you tell that the 89170-78020 is defective?

The defect in the 89170-78020 shows up on the airbag warning light in the instrument cluster, which lights up permanently or intermittently. A fault message in the instrument cluster, no connection to the diagnostic tool, or a fault memory that cannot be erased are added signs.

• Airbag warning light stays on permanently
• Airbag warning light only comes on intermittently
• Fault message in the instrument cluster
• Diagnostic tool cannot reach the control unit
• Fault memory cannot be erased

Such a picture does not necessarily mean the unit is a total loss, but it requires a test.

If the restraint system is disturbed, airbags and seatbelt pretensioners may fail to deploy in an emergency.

Which vehicles is the 89170-78020 fitted in?

Only the read-out fault memory reveals whether the unit is actually defective. The control unit 89170-78020 is fitted in these vehicles: Lexus NX AZ10 (2014-2017) and AZ10 Facelift (2017-2021).

Here are the models in which the control unit was installed:

• Lexus NX AZ10 (2014-2017)
• Lexus NX AZ10 Facelift (2017-2021)

First compare the part number on the label of the removed unit with this page. That only shows that you have the right unit, not the cause. Also have the fault memory read out, because the result shows whether the control unit is defective or whether a connector or cable is affected.

For the same vehicles, we also repair control units with the part numbers 89170-78010.

How does the repair of the 89170-78020 work?

At the start, have the fault memory read out and enclose the log. Only then disconnect the battery and remove the control unit 89170-78020. Then create a repair order online and send in the unit, well packed.

At Airbag24, the unit undergoes testing, repair of defective components, erasure of the crash data and a function test. After that, your own unit is returned to you.

Processing at Airbag24 usually takes 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 89170-78020 get to Airbag24?

A parcel is enough to send in the control unit 89170-78020, or you book a UPS collection for an extra charge. The unit comes back to you from Airbag24 by UPS.

Put the printed repair order into the parcel; the unit must be packed shock-proof.