Airbag control unit with part number 89170-42D91

What does the airbag control unit 89170-42D91 do?

The 89170-42D91 is the central control unit of the restraint system (SRS) for Toyota. It evaluates the signals from the crash sensors, decides in the event of a crash within milliseconds whether airbags and seatbelt pretensioners are triggered, and monitors the system continuously.

If the unit detects a fault, it reports it via the airbag warning light in the instrument cluster. The fault is also stored in the fault memory, so that it can be traced later. In this way the status of the system always remains retrievable.

After an accident the control unit stores crash data and locks itself. Whether this state is present becomes quickly apparent when the data is read out, because the unit then reacts differently than before.

Why does the control unit 89170-42D91 fail?

The most common cause is crash data stored after an accident, even if no airbag has deployed; a normal diagnostic tool cannot erase it. Aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes, for example from a weak battery or jump-starting, are also possible causes.

Crash data remains in the memory after an accident even if no airbag fired at all. An ordinary diagnostic tool cannot reach it, and that is exactly why the fault is so clearly visible when the data is read out. During the repair at Airbag24 the data is erased.

The other causes are rather everyday in nature. Electronic components age over time, solder joints can go cold, and at plug connections moisture and corrosion attack the contact. Voltage spikes additionally stress the electronics, especially when the battery is weak.

How can you tell that the 89170-42D91 is defective?

The airbag warning light in the instrument cluster lights up continuously or intermittently, a fault message appears in the instrument cluster, the diagnostic tool finds no connection to the control unit, or the fault memory cannot be cleared. In an emergency, airbags and seatbelt pretensioners may then fail to deploy.

The light is the most obvious sign you will encounter in everyday driving, and it should be taken seriously. If it goes out after the ignition is switched on, that is no reliable sign that everything is in order.

A diagnostic tool that cannot establish a connection, or a fault memory that cannot be emptied, also points to a problem in the system. Only reading out by a specialist workshop shows the actual status of the unit.

Which vehicles is the 89170-42D91 fitted in?

The 89170-42D91 is fitted in these vehicles: Toyota RAV4 XA50 (from 2018).

The following overview lists the vehicles recorded for this part number.

• Toyota RAV4 XA50 (from 2018)

The following steps will help you. Compare the part number on the label of the removed unit with this page; this way you ensure that it is the correct unit. Also have the fault memory read out beforehand, because only that 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 150800-4431, 152100-0262, 152100-4560, 89170-42400, 89170-42870, 89170-42A60.

How does the repair of the 89170-42D91 work?

First have the fault memory read out and enclose the log, then disconnect the battery and only then remove the 89170-42D91. Then create a repair order online and send in the well-packed unit; Airbag24 checks it on the test bench, replaces defective components, erases the crash data and carries out a functional test. Processing at Airbag24 usually takes 3–4 working days.

The log must go into the parcel, because it shows the testing team which faults were present. Make sure the sequence is followed, as the steps build on one another.

After the functional test your own, repaired unit is returned. 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 89170-42D91 get to Airbag24?

You send the 89170-42D91 in as a parcel or book a UPS collection in addition; after the repair Airbag24 sends it back to you by UPS.

Put the printed repair order into the parcel and pack the control unit shock-proof so that it arrives undamaged.