Airbag control unit with part number P8635A309

What does the airbag control unit P8635A309 do?

The airbag control unit P8635A309 coordinates the restraint system (SRS) of Mitsubishi. It reads the signals from the crash sensors, decides within milliseconds in an emergency whether airbags and seatbelt pretensioners trigger, and monitors the whole system.

It detects faults itself and shows them via the airbag warning light in the instrument cluster. This keeps it visible to the driver and the workshop that something is wrong with the system.

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

Why does the control unit P8635A309 fail?

The P8635A309 most often fails because of stored crash data, even if no airbag was triggered. Other possible causes are aged electronic components, cold solder joints, moisture or corrosion on plug connections, and voltage spikes.

Crash data is stored in the unit's memory after an accident and cannot be removed with a standard diagnostic tool. Airbag24 erases it deliberately during the repair.

The other causes concern the electrics. A control unit reacts sensitively to voltage spikes, for example from a weak battery or after a jump-start, and to moisture or rust on the plug connections.

How can you tell that the P8635A309 is defective?

A defect on the P8635A309 shows itself through the airbag warning light in the instrument cluster, which stays on permanently or intermittently, and through fault messages on the display. Even if the diagnostic tool cannot establish a connection to the control unit, or the fault memory cannot be cleared, a problem is present.

In an emergency, airbags and seatbelt pretensioners may then fail to trigger. For that reason, do not ignore a lit warning light, and have it checked promptly.

Which vehicles is the P8635A309 fitted in?

The P8635A309 is fitted in these vehicles: Mitsubishi Lancer CY (2007-2017). The assignment is based on the part number, not on the model name alone.

These vehicles are assigned to the part number:

• Mitsubishi Lancer CY (2007-2017)

Compare the part number on the label of the removed unit with this page, and you will see that you have the right unit in front of you. Whether the control unit itself is defective, or a plug or cable is causing the fault, is shown only by the fault memory. Have it read out beforehand.

For the same vehicles, we also repair control units with the part numbers P8635A146, P8635A168, TARME1308R0924, TARME2937R0152.

How does the repair of the P8635A309 work?

First have the fault memory read out and attach the protocol, then disconnect the battery and only then remove the control unit. Afterwards, create a repair order online and send in the unit, well packed. Checking, repairing and testing at Airbag24 usually take 3–4 working days.

On the test bench, Airbag24 examines the unit, repairs the defective components and erases the stored crash data. A function test follows. Afterwards the unit goes back 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 P8635A309 get to Airbag24?

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

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