Airbag control unit with part number 89170-52K40

What does the airbag control unit 89170-52K40 do?

The 89170-52K40 works as the airbag control unit and forms the control centre of the restraint system (SRS) at Toyota. It detects an accident from the crash sensors and triggers the appropriate airbags and seatbelt pretensioners within milliseconds. It monitors the system continuously, reports faults via the airbag warning light, and after an accident stores crash data and locks itself.

The unit is connected to sensors, trigger circuits and seatbelt pretensioners and checks these connections continuously.

Its task is safety-relevant, which is why faults must be taken seriously.

Why does the control unit 89170-52K40 fail?

On the 89170-52K40, the most frequent cause of a fault is crash data stored after an accident, even if no airbag has triggered; they cannot be erased with a normal diagnostic tool. Other causes are aged electronics, cold solder joints, moisture and corrosion at plugs, and voltage spikes.

Stored crash data remain in the unit, even while the vehicle is back in everyday use.

The other causes at a glance:

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

How can you tell that the 89170-52K40 is defective?

The airbag warning light in the instrument cluster lights up on the 89170-52K40 constantly or comes on intermittently. In addition there are an error message, no communication with the diagnostic tool, and a fault memory that cannot be cleared. In an emergency, the airbags and seatbelt pretensioners may then fail to deploy.

These signs occur individually or in combination:

• Airbag warning light stays on in the instrument cluster
• Error message in the instrument cluster
• Diagnostic tool without connection to the control unit
• Fault memory cannot be cleared

Which vehicles is the 89170-52K40 fitted in?

The following vehicles are equipped with the 89170-52K40: Toyota Aqua NHP10 (2011-2015), NHP10 1st Facelift (2015-2017) and NHP10 2nd Facelift (2017-2021).

The vehicles in detail:

• Toyota Aqua NHP10 (2011-2015)
• Toyota Aqua NHP10 1st Facelift (2015-2017)
• Toyota Aqua NHP10 2nd Facelift (2017-2021)

First compare the label of the removed unit with this page, so that you can see it matches the details. Then have the fault memory read out, because only this log shows whether the control unit or a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 152100-4560, 89170-42D50.

How does the repair of the 89170-52K40 work?

For the 89170-52K40, the sequence is: read out the fault memory and attach the log, disconnect the battery, only then remove the control unit, create the repair order online and send in the unit well packed. Checking, repairing and testing at Airbag24 usually take 3–4 working days.

Airbag24 checks the unit on the test bench, replaces defective components, deletes stored crash data and carries out a function test.

Afterwards, your own, repaired unit is returned 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 89170-52K40 get to Airbag24?

The 89170-52K40 reaches Airbag24 as a parcel, or you book a UPS collection for an extra charge. After the repair, Airbag24 returns it by UPS.

Put the printed repair order into the parcel; pack the unit shock-proof.