Airbag control unit with part number 77960-TWD-J520-M4

What does the airbag control unit 77960-TWD-J520-M4 do?

As the evaluation unit of the restraint system (SRS) for Honda, the airbag control unit 77960-TWD-J520-M4 forms the centre. It processes the crash sensors, determines within milliseconds in an accident which airbags and seatbelt pretensioners fire, and monitors the system continuously.

It indicates faults via the airbag warning light in the instrument cluster. Every message from this light deserves attention.

After an accident the unit writes crash data permanently, and the result is that the unit is locked.

Why does the control unit 77960-TWD-J520-M4 fail?

Stored crash data is the most common cause of the 77960-TWD-J520-M4 failing, even when no airbag has deployed. Ageing electronics, contact problems and voltage spikes are added to this.

A control unit keeps crash data until it is removed. An ordinary diagnostic tool cannot do this. Airbag24 deletes this data during the repair.

Electronic components lose reliability over the years, soldered joints can be dry joints, and moisture together with corrosion attacks plug connections. Voltage spikes when starting, for example with a weak battery or jump-starting, come on top of this.

How can you tell that the 77960-TWD-J520-M4 is defective?

A defect in the 77960-TWD-J520-M4 is indicated by an airbag warning light in the instrument cluster that stays on permanently or intermittently. Further signs are an error message, a lack of connection to the diagnostic tool and a fault memory that cannot be cleared.

The light alone is the clearest sign, and it is accompanied by an error message in the instrument cluster. If the diagnostic tool cannot establish a connection to the control unit, or the fault memory cannot be cleared, this also points to a problem.

In an emergency, airbags and seatbelt pretensioners may fail to deploy in the event of a defect of this kind. If you see any of these signs, do not ignore them.

Which vehicles is the 77960-TWD-J520-M4 fitted in?

Vehicles with the 77960-TWD-J520-M4 include: Honda Accord 10th generation (2017-2024).

The assignment is shown in this list:

• Honda Accord 10th generation (2017-2024)

The label comparison only confirms that the unit matches this page, i.e. that it is the right one. Only the read-out fault memory reliably shows whether the control unit is defective or whether a connector or cable is the cause. Therefore have it read out before removal.

For the same vehicles, we also repair control units with the part numbers 77960-T3L-A012-M1, 77960-T3L-C012-M4, 77960-T3L-C020-M4, 77960-T3L-C030-M4, 77960-T3L-F012-M4, 77960-T3L-F020-M4.

How does the repair of the 77960-TWD-J520-M4 work?

First the fault memory is read out, then the battery is disconnected and finally the control unit 77960-TWD-J520-M4 is removed. Processing at Airbag24 usually takes 3–4 working days.

Online you then create the repair order; the unit is packed carefully afterwards.

Airbag24 checks the unit on the test bench, replaces defective components, deletes crash data and carries out a function test. Your repaired unit is then returned to you.

The sequence during removal is binding for safety reasons. 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 77960-TWD-J520-M4 get to Airbag24?

Your route runs via a parcel: you send the control unit 77960-TWD-J520-M4 yourself, or you commission UPS collection for an extra charge. Airbag24 sends it back by UPS after the repair.

Put the printed repair order in with it and protect the unit from knocks.