Airbag control unit with part number 89170-50L73

What does the airbag control unit 89170-50L73 do?

The airbag control unit 89170-50L73 forms the central control unit of the restraint system (SRS) for Lexus. It processes the signals from the crash sensors, determines within milliseconds in the event of a crash which airbags and seatbelt pretensioners are triggered, and checks the entire system continuously. If it detects a fault, the airbag warning light comes on.

Monitoring runs without interruption while the vehicle is in use. Irregularities in sensors, wiring and plugs are recorded in the fault memory.

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

Why does the control unit 89170-50L73 fail?

The stored crash data is the most common cause, even if no airbag was triggered. A normal diagnostic tool does not make it disappear. Other causes include ageing electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes, for example from a weak battery or jump-starting.

The crash data stays stored in the control unit until it is deliberately cleared. An ordinary diagnostic tool cannot do that.

The other causes develop over a long time: the electronics age, solder joints can stay cold, and moisture attacks plug connections. Voltage spikes from a weak battery or jump-starting can also lead to a failure.

How can you tell that the 89170-50L73 is defective?

The airbag warning light in the instrument cluster stays on constantly or intermittently, and an error message appears. The diagnostic tool finds no connection to the control unit, or the fault memory cannot be cleared. In that case, the airbags and seatbelt pretensioners may fail to trigger in an emergency.

These signs point to a fault in the restraint system, but they do not automatically mean that the control unit itself is affected. A plug or a cable can also be the cause.

Should any of these signs appear, have the fault memory read out.

Which vehicles is the 89170-50L73 fitted in?

The information relates to this part number alone. The 89170-50L73 is fitted in these vehicles: Lexus LS XF50 (from 2018).

You will find the vehicles in this overview:

• Lexus LS XF50 (from 2018)

Compare the part number on the label of the removed unit with this page so that you can be sure you have the right unit. Whether the control unit is defective, or whether a plug or a cable is the cause, is shown only by the fault memory read out beforehand.

For the same vehicles, we also repair control units with the part numbers 89170-50K81, 89170-50K83, 89170-50L00, 89170-50L03, 89170-53790, 89170-53820.

How does the repair of the 89170-50L73 work?

First have the fault memory read out and enclose the log. Then disconnect the battery, remove the control unit and create a repair order online. Checking, repairing and testing at Airbag24 usually take 3–4 working days.

Send the unit off well packed. Airbag24 checks it on the test bench, replaces defective components, clears the stored crash data and carries out a function test. Your own unit is then 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 89170-50L73 get to Airbag24?

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

Put the printed repair order into the parcel and pack the unit securely against impact.