Airbag control unit with part number 89170-F4090

What does the airbag control unit 89170-F4090 do?

The airbag control unit 89170-F4090 is the central control unit of the restraint system (SRS) for Toyota. It processes the signals from the crash sensors and decides in an accident within milliseconds which airbags and seatbelt pretensioners are triggered. After an accident, it stores crash data and locks itself.

The unit checks the system continuously for irregularities. If it detects a fault, it writes this to the fault memory and displays it via the airbag warning light.

In a crash, the electronics follow a fixed program, so a defect affects the entire protective effect in the vehicle.

Why does the control unit 89170-F4090 fail?

The most common cause is crash data stored after an accident, even if no airbag was triggered. A normal diagnostic tool cannot erase it. Other causes are aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes.

The crash data remains in the unit until Airbag24 removes it during repair. This applies regardless of how the accident affected the vehicle.

The other causes arise over time. Components age, solder joints can go cold, moisture attacks the connectors, and voltage spikes from a weak battery or jump-starting stress the electronics.

How can you tell that the 89170-F4090 is defective?

A defect on the 89170-F4090 shows through the airbag warning light in the instrument cluster, which stays on permanently or intermittently, and through an error message in the instrument cluster. In addition, the diagnostic tool gets no connection to the control unit, and the fault memory cannot be cleared.

The light is the clearest sign that the restraint system has detected a fault. Depending on the fault, it stays on permanently or only now and then.

In an emergency, the airbags and seatbelt pretensioners may fail to deploy. You should therefore have such signs checked promptly.

Which vehicles is the 89170-F4090 fitted in?

The 89170-F4090 is fitted in these vehicles: Toyota C-HR NGX10 (2017-2019).

The list below shows the assigned vehicles.

• Toyota C-HR NGX10 (2017-2019)

Compare the part number on the label of the removed unit with this page. This only ensures that you have the correct unit. Also have the fault memory read out in advance, because only this log shows whether the control unit is defective or a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 89170-F4210, 8917010110.

How does the repair of the 89170-F4090 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 in. Airbag24 checks it, replaces defective components, erases the crash data and carries out a function test.

The sequence is mandatory for safety reasons, so keep to it.

At Airbag24, the unit is examined on the test bench and then tested. Your unit is then returned to you. Processing usually takes 3–4 working days, and this time covers only the checking, repairing and testing at Airbag24. 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-F4090 get to Airbag24?

You send the control unit 89170-F4090 in as a parcel or book a UPS collection for an extra charge. After repair, Airbag24 sends it back to you by UPS.

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