Airbag control unit with part number 89170-48540

What does the airbag control unit 89170-48540 do?

The airbag control unit 89170-48540 controls the airbags and seatbelt pretensioners of the restraint system (SRS) in Lexus. The measured values of the crash sensors come together in it, and in an accident it makes the triggering decision within milliseconds. During operation it monitors the system; faults appear on the airbag warning light.

The evaluation takes place in fractions of a second. In addition, the unit checks whether the connections and the power supply are in order.

After an accident, it stores crash data and locks itself.

Why does the control unit 89170-48540 fail?

The most common cause is crash data from an accident, even if no airbag was triggered; an ordinary diagnostic tool cannot delete it. Further triggers are the ageing of components, cold solder joints, moisture in plug contacts and voltage spikes, such as can occur with a weakened battery or jump-starting.

Crash data remains in the memory even when the airbags stayed quiet. It reveals nothing from the outside.

The other sources of fault act through everyday use: electronics age, connections become susceptible and voltages fluctuate. With a jump-start or a weak battery, current spikes can occur that affect the control unit.

How can you tell that the 89170-48540 is defective?

A defect is indicated by the airbag warning light in the instrument cluster, which stays on permanently or intermittently, and by an error message in the display. If the diagnostic tool does not communicate with the control unit at all, or the fault memory cannot be emptied, this points to a fault. Airbags and seatbelt pretensioners may then possibly fail to trigger in an emergency.

The warning light is among the most important warning signals in the car, because it concerns the entire restraint system. If it does not go out after the ignition is switched on, have the finding checked.

An error message in the display also counts, even if the light goes out in between, because the fault memory records the finding.

Which vehicles is the 89170-48540 fitted in?

The control unit 89170-48540 is fitted at Lexus in this selection: Lexus RX AL10 Facelift (2012-2015) and AL10 (2009-2012). The comparison of the part number applies to the removed unit itself.

The compilation of the models on record follows below.

• Lexus RX AL10 Facelift (2012-2015)
• Lexus RX AL10 (2009-2012)

Compare the part number on the label of the removed unit with this page. This only confirms the identity of the unit and says nothing about the cause. Therefore have the fault memory read out beforehand, because the result shows whether the control unit itself is defective or whether a plug or a cable is the cause.

For the same vehicles, we also repair control units with the part numbers 1503001853, 8917048380.

How does the repair of the 89170-48540 work?

First you read out the fault memory and attach the log, then you disconnect the battery and remove the control unit. Next, create the repair order online and send the unit off well packed. For checking, repair and function testing at Airbag24, 3–4 working days are usually planned.

Airbag24 examines the submitted control unit on the test bench and repairs defective components. Afterwards Airbag24 deletes the stored crash data, carries out a function test and returns your own unit.

The sequence on the vehicle serves safety. 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 89170-48540 get to Airbag24?

You send the control unit 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; the unit is packed so that it withstands knocks.