Airbag control unit with part number 77960-TVA-Q420-M4

What does the airbag control unit 77960-TVA-Q420-M4 do?

The airbag control unit 77960-TVA-Q420-M4 controls the restraint system (SRS) in Honda. It evaluates the signals from the crash sensors, decides within milliseconds in the event of an accident which airbags and seatbelt pretensioners are triggered, and monitors the system continuously. If it detects a fault, it reports it via the airbag warning light.

In normal operation this monitoring runs in the background while the vehicle is switched on. Sensors, wiring and trigger circuits are checked in the process.

After an accident the control unit stores crash data and locks itself. The consequences of this lock for everyday driving are summarised in the section on the signs of a defect.

Why does the control unit 77960-TVA-Q420-M4 fail?

The most common cause is crash data stored after an accident, even if no airbag has deployed; a standard diagnostic tool cannot erase it. Other causes include ageing electronics, moisture and corrosion at plug connectors, and voltage spikes.

Airbag24 erases the crash data as part of the repair. The other causes at a glance:

• aged electronic components,
• cold solder joints on the circuit board,
• moisture and corrosion at plug connectors,
• voltage spikes, for example from a weak battery or when connecting to a jump start.

How can you tell that the 77960-TVA-Q420-M4 is defective?

A defect is signalled by the airbag warning light in the instrument cluster, either permanently or intermittently. Other signs can include an error message in the instrument cluster, no connection between the diagnostic tool and the control unit, or a fault memory that cannot be cleared.

Check the warning light directly after switching on the ignition, and have a permanent display examined promptly. In an emergency, the airbags and seatbelt pretensioners may then fail to deploy.

An error message in the display complements this indication. If there is no connection to the diagnostic tool, a cable or plug may be affected as well as the control unit itself.

Which vehicles is the 77960-TVA-Q420-M4 fitted in?

The airbag control unit 77960-TVA-Q420-M4 is fitted in these vehicles: Honda Accord 10th generation (2017-2024).

The overview below lists the vehicles recorded for this part number:

• Honda Accord 10th generation (2017-2024)

First compare the part number on the label of the removed unit with this page; this only ensures that you have the correct unit. Have the fault memory read out beforehand, because only this log shows whether the control unit is defective or whether a plug or cable is the cause.

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-TVA-Q420-M4 work?

First have the fault memory read out and attach the log. Then disconnect the battery and remove the control unit in the last step. Next, create a repair order online, pack the unit well and send it in.

At Airbag24 the unit first goes through the test bench. There, defective components are repaired, stored crash data is erased and a functional test is carried out. Processing at Airbag24 usually takes 3–4 working days, after which your own unit is sent 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 77960-TVA-Q420-M4 get to Airbag24?

You either hand in the control unit 77960-TVA-Q420-M4 as a parcel, or book a UPS collection for an extra charge. After the repair, Airbag24 sends it back by UPS.

Put the printed repair order in the parcel and pack the unit shockproof before it goes on its way.