Airbag control unit with part number 77960-TWA-L420-M4

What does the airbag control unit 77960-TWA-L420-M4 do?

The airbag control unit 77960-TWA-L420-M4 is the central control of the restraint system (SRS) in Honda. It evaluates the crash sensors, determines in an accident which airbags and seatbelt pretensioners are triggered, and monitors the entire system. After an accident it stores crash data and locks itself.

If the control unit detects a fault, it reports it via the airbag warning light in the instrument cluster. The evaluation runs in the background, so in everyday use you usually notice nothing of it.

Why does the control unit 77960-TWA-L420-M4 fail?

The most common cause is crash data after an accident, even if no airbag was triggered; an ordinary diagnostic tool cannot erase it. Alongside this, ageing components, solder joints, moisture at connectors and voltage spikes come into question.

Crash data arises during the accident and remains in the control unit afterwards, without an airbag having to trigger. The other causes at a glance:

• Electronics that weaken over time
• Solder joints with damage
• Moisture or corrosion at plug connections
• Voltage spikes, for example with a weak battery or a jump start

How can you tell that the 77960-TWA-L420-M4 is defective?

A defect shows itself mainly through the airbag warning light in the instrument cluster, which lights up permanently or intermittently, through a fault message in the instrument cluster, or through a missing contact to the diagnostic tool. A fault memory that cannot be cleared also indicates a fault. In an emergency, airbags and seatbelt pretensioners may then not trigger.

The signs in detail:

• Airbag warning light lights up permanently
• Airbag warning light lights up only intermittently
• Fault message in the instrument cluster
• Diagnostic tool cannot reach the control unit
• Fault memory cannot be cleared

Have a warning checked promptly, even if the vehicle otherwise runs normally.

Which vehicles is the 77960-TWA-L420-M4 fitted in?

The 77960-TWA-L420-M4 is used in these vehicles: Honda Accord 10th generation (2017-2024). You check from the list whether your car is one of them.

This listing shows the vehicles for which the control unit is intended:

• Honda Accord 10th generation (2017-2024)

Compare the part number on the label of the removed unit with this page. This only confirms that it is the right unit, nothing more. Also have the fault memory read out in advance, because only that result shows whether the control unit is defective or whether a connector or a cable is causing the fault.

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-TWA-L420-M4 work?

For the 77960-TWA-L420-M4, follow this order: first have the fault memory read out and enclose the log, then disconnect the battery. Only after that do you remove the control unit and create a repair order online. Then send in the well-packed unit.

The log belongs with the order, so that Airbag24 knows the history. Disconnecting the battery before removal is a safety measure.

At Airbag24, the control unit is examined on the test bench, defective components are repaired, stored crash data is deleted, and a function test concludes the work. Processing usually takes 3–4 working days. Afterwards your own 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 77960-TWA-L420-M4 get to Airbag24?

You hand in the control unit 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 protect the control unit with shock-resistant packaging.