Airbag control unit with part number 89170-33S40

What does the airbag control unit 89170-33S40 do?

The 89170-33S40 is the central airbag control unit of the SRS for Lexus. It evaluates the crash sensors, decides in an accident on the triggering of airbags and seatbelt pretensioners, and monitors the entire system during operation. After an accident it stores crash data and locks itself.

It works together with sensors, wiring and the connected firing circuits. Faults are indicated in the instrument cluster via the airbag warning light.

Why does the control unit 89170-33S40 fail?

Stored crash data is the most common cause on the 89170-33S40, even if no airbag has deployed, and a normal diagnostic tool cannot erase it. Beyond that, further causes come into consideration that affect the electronics themselves.

The overview lists these points:

• ageing electronic components
• cold solder joints on the circuit board
• moisture and corrosion on plug connections
• voltage spikes, for example from a weak battery or jump-starting

Crash data are entries in the memory and not damage to the housing.

How can you tell that the 89170-33S40 is defective?

The airbag warning light in the instrument cluster lights up on the 89170-33S40 permanently or intermittently, and a fault message appears there. The diagnostic tool may find no connection to the control unit, and the fault memory cannot be erased. In an emergency, airbags and seatbelt pretensioners may then fail to deploy.

The warning light is the clearest sign, because it is in view on every journey. The other hints complete the picture, but only the read-out of the fault memory clarifies the cause.

Which vehicles is the 89170-33S40 fitted in?

The 89170-33S40 is fitted in these vehicles: Lexus ES AXZH60 (from 2018).

Here follows the list of vehicles for this part number:

• Lexus ES AXZH60 (from 2018)

Compare the part number on the label of the removed unit with this page; that only ensures that it is the right unit. A prior read-out of the fault memory, on the other hand, shows whether the control unit itself is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 89170-06820, 89170-06850, 89170-06880, 89170-33B90, 89170-33C30, 89170-33C50.

How does the repair of the 89170-33S40 work?

First have the fault memory read out and enclose the log. Then disconnect the battery, only then remove the control unit 89170-33S40, and create the repair order online.

Next you send the unit in well packed. Airbag24 checks it on the test bench, repairs defective components, erases stored crash data and runs a function test; afterwards your own unit goes back to you.

For checking, repairing and testing at Airbag24 you should allow 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 89170-33S40 get to Airbag24?

You send the 89170-33S40 as a parcel or book a UPS collection for an extra charge, and Airbag24 returns it to you by UPS after the repair.

The printed repair order belongs in the parcel, and you pack the unit shock-resistant.