Airbag control unit with part number 89170-42D51

What does the airbag control unit 89170-42D51 do?

The airbag control unit 89170-42D51 is the central control unit of the restraint system (SRS) for Toyota. In an impact it evaluates the signals from the crash sensors and decides within milliseconds which airbags and seatbelt pretensioners are triggered.

Even without an accident the unit works constantly: it monitors all connected components and reports faults via the airbag warning light in the instrument cluster.

After an accident the control unit stores crash data and locks itself. You notice nothing of this during normal driving; during a diagnosis the lock becomes apparent immediately.

Why does the control unit 89170-42D51 fail?

The most common cause is crash data stored after an accident, even if no airbag was triggered. A usual diagnostic tool cannot remove it. Further 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.

A diagnostic tool cannot delete the data, so the cause remains in the unit. The failure therefore originates in the control unit itself.

Aged components and cold solder joints can cause faults on their own. Voltage spikes from the vehicle electrical system also strain the electronics.

How can you tell that the 89170-42D51 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently, a fault message appears in the instrument cluster, and the diagnostic tool does not reach the control unit. A fault memory that cannot be cleared is a further sign.

The light is a clear indication, because it makes every detected fault visible. The signs are based on the system's self-monitoring and are not a mere assumption.

As long as the defect exists, airbags and seatbelt pretensioners may possibly fail to trigger in an emergency. A prompt check is therefore advisable.

Which vehicles is the 89170-42D51 fitted in?

Our assignment is based on the data recorded so far. The control unit 89170-42D51 is fitted in these vehicles: Toyota RAV4 XA50 (from 2018).

The list covers the vehicles recorded so far and does not claim to be complete. The vehicles recorded individually:

• Toyota RAV4 XA50 (from 2018)

Compare the part number on the label of the removed unit with this page; this only confirms that it is the correct unit. Also have the fault memory read out beforehand, because only that result shows whether the control unit is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 150800-4431, 152100-0262, 152100-4560, 89170-42400, 89170-42870, 89170-42A60.

How does the repair of the 89170-42D51 work?

First have the fault memory read out and enclose the log. Then disconnect the battery and only then remove the control unit. Next create a repair order online and send the well-packed unit; Airbag24 checks it, repairs defective components, deletes crash data and tests the unit.

The order is mandatory, because it serves safety. For checking, repairing and testing at Airbag24 we expect 3–4 working days as a rule.

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 89170-42D51 get to Airbag24?

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

Enclose the printed repair order and pack the unit so that it arrives shock-resistant.