Airbag control unit with part number 89170-42A20

What does the airbag control unit 89170-42A20 do?

The airbag control unit 89170-42A20 forms the control centre of the SRS restraint system in vehicles from Toyota. It recognises a crash from the sensor signals and then decides, in a fraction of a second, which airbags and seatbelt pretensioners fire.

Between events, it monitors the entire system. It stores every fault it detects and makes it visible via the airbag warning light.

After an accident, the unit stores crash data and then locks itself.

Why does the control unit 89170-42A20 fail?

With the 89170-42A20, stored crash data is the most common cause, even if no airbag was triggered in the accident. Ageing components, moisture on the plugs and voltage spikes also play a role.

A standard diagnostic tool cannot remove the crash data. Airbag24 erases it during the repair.

Electronic components age over time, and dry solder joints can form on the circuit board. Moisture and corrosion at plug connections are also typical weak points.

Voltage spikes, for example from a weak battery or an improper jump start, place additional strain on the electronics.

How can you tell that the 89170-42A20 is defective?

Typical signs of a fault in the 89170-42A20 are a fault message in the instrument cluster, an airbag warning light that stays on permanently or only intermittently, and a diagnostic tool with no connection to the control unit. In this condition, the airbags and seatbelt pretensioners may not deploy in an emergency.

The list shows how you can recognise a fault:

• Airbag warning light in the instrument cluster stays on permanently
• Airbag warning light comes on only intermittently
• Fault message in the instrument cluster
• Diagnostic tool does not find the control unit
• Fault memory cannot be cleared

The warning light is the most important signal the vehicle gives. The finding should be checked promptly, because the system must work fully in an emergency.

Which vehicles is the 89170-42A20 fitted in?

The control unit 89170-42A20 is fitted in these vehicles: Toyota RAV4 XA50 (from 2018). The assignment is based on the data we hold for this unit.

The list shows the vehicles we have assigned to this control unit.

• Toyota RAV4 XA50 (from 2018)

Compare the part number on the label of the removed unit with this page. This way you can confirm that you have the right unit in front of you.

Also have the fault memory read out before you remove anything. The log shows whether the control unit is defective or whether a connector 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 89170-42A20 work?

Have the fault memory read out and enclose the log, then disconnect the battery and only then remove the control unit 89170-42A20. Next, create a repair order online and send the unit in well packed. Processing at Airbag24 takes 3–4 working days as a rule.

This sequence is for safety and is binding for all steps. The control unit may only be removed from the vehicle once the battery has been disconnected.

Airbag24 checks the unit on the test bench, replaces defective components, erases the stored crash data and carries out a functional test. The unit then goes back to you.

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 89170-42A20 get to Airbag24?

You send the unit 89170-42A20 as a parcel or book a UPS collection for an extra charge. Airbag24 returns it to you by UPS after the repair.

The printed repair order goes in the parcel. Pack the unit shockproof so that it arrives undamaged.