Airbag control unit with part number 89170-42D40

What does the airbag control unit 89170-42D40 do?

The airbag control unit 89170-42D40 is the control unit of the restraint system for Toyota. It processes the crash sensor data and determines in an accident which airbags and seatbelt pretensioners are triggered. It signals faults via the airbag warning light.

The unit continuously checks whether all components are working plausibly.

After an accident it stores crash data and locks itself.

Why does the control unit 89170-42D40 fail?

The most common cause of the 89170-42D40 is the storage of crash data, even if no airbag has deployed. A normal diagnostic tool does not delete this data. Other causes are ageing, solder joints, moisture and voltage spikes.

The other causes in detail:

• ageing of the electronic components
• cold solder joints
• moisture and corrosion at plug connections
• voltage spikes, for example from a weak battery or a jump start

Crash data remains in the unit, regardless of whether an airbag has deployed in the accident. Looking at the plugs and cables alone therefore does not answer the question of the cause.

How can you tell that the 89170-42D40 is defective?

A defect on the 89170-42D40 becomes visible at the airbag warning light in the instrument cluster, which lights up constantly or at times. In an emergency, airbags and seatbelt pretensioners may fail to trigger.

Typical signs at a glance:

• airbag warning light that lights up constantly or at times
• error message in the instrument cluster
• diagnostic tool with no connection to the control unit
• fault memory that cannot be cleared

The light is there precisely to make faults visible, so every indication from this area deserves a prompt check.

Which vehicles is the 89170-42D40 fitted in?

The assignment applies to Toyota. The control unit 89170-42D40 is fitted in these vehicles: Toyota RAV4 XA50 (from 2018).

The vehicle list is here:

• Toyota RAV4 XA50 (from 2018)

Comparing the part number on the label of the removed unit with this page only confirms that it is the matching unit; it does not establish the condition. Only the fault memory read out beforehand answers whether the unit is defective. A plug or a cable can equally be 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 89170-42D40 work?

First have the fault memory of the 89170-42D40 read out and enclose the log. Then disconnect the battery and remove the unit. Next create a repair order online and send in the well-packed unit. Processing at Airbag24 usually takes 3–4 working days.

Online you create the repair order, then you send in the packed unit. Airbag24 checks it, repairs defective components, deletes the stored crash data and carries out a function test. After that you receive your own unit back.

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 89170-42D40 get to Airbag24?

The control unit 89170-42D40 reaches Airbag24 by parcel or via a UPS collection booked for an extra charge. The return is made by UPS.

Put the printed repair order into the parcel and pack the unit shockproof.