Airbag control unit with part number 77960-T2A-A021-M4

What does the airbag control unit 77960-T2A-A021-M4 do?

The airbag control unit 77960-T2A-A021-M4 evaluates the sensor signals in the restraint system (SRS) of Honda. In an accident it determines which airbags and seatbelt pretensioners are triggered, and it monitors the system constantly. It reports faults via the airbag warning light.

The evaluation has to happen very quickly so that protection takes effect in time. To this end, the unit constantly compares the measured values with stored limit values.

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

Why does the control unit 77960-T2A-A021-M4 fail?

Crash data from an earlier accident is the most common cause, even if no airbag was triggered. A normal diagnostic tool cannot delete it. Other causes are ageing electronics, cold solder joints, moisture and voltage spikes at the plugs.

Stored crash data remains in the control unit after an accident, even if no airbag was triggered. It cannot be removed by ordinary means, which is why the fault persists.

The other causes concern the electronics. Ageing components, cold solder joints and moisture at plug connections are as much a factor as voltage spikes, for example from a weak battery or a jump start.

How can you tell that the 77960-T2A-A021-M4 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently. In addition, the instrument cluster shows fault messages, and the fault memory cannot be cleared.

Typical signs are:

• Airbag warning light, permanently or intermittently on
• Fault message in the instrument cluster
• Diagnostic tool cannot find the control unit
• Fault memory cannot be cleared

In an emergency, airbags and seatbelt pretensioners may therefore not deploy. Check the message promptly.

Which vehicles is the 77960-T2A-A021-M4 fitted in?

The assignment applies to Honda. The control unit 77960-T2A-A021-M4 is fitted in these vehicles: Honda Accord 9th generation (2012-2019).

These vehicles are on record:

• Honda Accord 9th generation (2012-2019)

Compare the part number on the label of the removed unit with this page. This tells you that you have the right unit. Have the fault memory read out beforehand, because it shows whether the control unit is defective or whether a plug or cable is causing the fault.

For the same vehicles, we also repair control units with the part numbers 77960-SEA-G815-M1, 77960-T3L-A012-M1, C0W6K4VDA.

How does the repair of the 77960-T2A-A021-M4 work?

First have the fault memory read out and enclose the log. Then disconnect the battery, and only then remove the control unit. Next create a repair order online and pack the unit well before sending it. Processing at Airbag24 usually takes 3–4 working days.

Airbag24 inspects the unit on the test bench and replaces only the defective components. The stored crash data is then deleted, followed by a functional test.

The unit is then 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-T2A-A021-M4 get to Airbag24?

You send the unit as a parcel or book UPS collection for an extra charge. Airbag24 returns the repaired unit to you by UPS.

Enclose the printed repair order in the parcel and pack the unit shock-resistant.