Airbag control unit with part number 89170-42840

What does the airbag control unit 89170-42840 do?

The airbag control unit 89170-42840 is the central control unit of the restraint system (SRS) in Toyota. It processes sensor signals, determines in a crash whether airbags and seatbelt pretensioners fire, and monitors the system constantly. After an accident it stores crash data and locks itself.

The control unit completes its tasks quickly: the deployment decision takes only milliseconds. In everyday use it stays in the background, but it reports faults via the airbag warning light.

Why does the control unit 89170-42840 fail?

The most common cause in the 89170-42840 is crash data stored after an accident, which cannot be erased with a normal diagnostic tool. Aged components, corrosion on plugs and voltage spikes are also possible.

Crash data are stored even when no airbag has deployed in the accident. That is why the fault memory alone does not give the full picture.

The other causes concern the electronics. Components age, moisture and corrosion attack plug connections, and voltage spikes arise, for example, with a weak battery or during a jump start.

How can you tell that the 89170-42840 is defective?

A defect in the 89170-42840 shows up as the airbag warning light, as error messages and as the diagnostic tool failing to establish a connection. In an emergency, the airbags and seatbelt pretensioners may then fail to deploy.

The following signs indicate a defect:

• the airbag warning light in the instrument cluster stays on permanently or intermittently
• an error message appears in the instrument cluster
• the diagnostic tool does not find the control unit
• the fault memory cannot be cleared

Which vehicles is the 89170-42840 fitted in?

The control unit 89170-42840 is used in these vehicles: Toyota RAV4 XA50 (from 2018).

The assignment by part number gives this list:

• Toyota RAV4 XA50 (from 2018)

Matching the part number on the label of the removed unit with this page ensures that you have the correct unit. Whether the control unit is defective, or whether a plug or cable is the cause, is shown only by reading out the fault memory. This reading must therefore take place beforehand, before removal.

For the same vehicles, we also repair control units with the part numbers 150800-4431, 152100-0262, 152100-4560, 89170-0R070, 89170-0R090, 89170-0R091.

How does the repair of the 89170-42840 work?

First have the fault memory of the 89170-42840 read out and attach the log. Then disconnect the battery, remove the control unit, create a repair order online and pack the unit well. At Airbag24, inspection and repair usually take 3–4 working days.

At Airbag24, the unit is examined on the test bench and defective components are repaired. The stored crash data are erased, followed by a functional test. Your own unit is then returned to you. The order at the start serves safety.

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 89170-42840 get to Airbag24?

You send the control unit 89170-42840 in as a parcel, or book a UPS collection for an extra charge. After the repair, Airbag24 sends it back by UPS.

Put the printed repair order into the parcel and pack the unit shock-proof. This keeps it well protected for transport.