Airbag control unit with part number 77960-T3L-C020-M4

What does the airbag control unit 77960-T3L-C020-M4 do?

The 77960-T3L-C020-M4 is the central control unit of the restraint system (SRS) of Honda. It processes the signals from the crash sensors and decides in an accident, within milliseconds, which airbags and seatbelt pretensioners are triggered.

During operation the unit monitors the entire system. If it detects a fault, it reports it via the airbag warning light in the instrument cluster.

After an accident the control unit stores crash data and locks itself. This lock is only lifted by the repair.

Why does the control unit 77960-T3L-C020-M4 fail?

The most common cause for the 77960-T3L-C020-M4 lies in crash data stored after an accident, even if no airbag was triggered. Other causes are ageing electronic components, cold solder joints, moisture or corrosion at plug connections, and voltage spikes.

This crash data cannot be removed with a normal diagnostic tool. Airbag24 clears it during the repair.

The other causes in detail are:

• ageing electronic components
• cold solder joints
• moisture and corrosion at plug connections
• voltage spikes, for example from a weak battery or a jump start

How can you tell that the 77960-T3L-C020-M4 is defective?

In the 77960-T3L-C020-M4, the airbag warning light in the instrument cluster lights up permanently or intermittently. Added to this are a fault message in the instrument cluster, no connection between the diagnostic tool and the control unit, and a fault memory that cannot be cleared.

The airbag warning light is the most important warning sign: it lights up permanently or only intermittently, and the diagnostic tool then gets no connection. If you continue driving with such a fault, airbags and seatbelt pretensioners may possibly not deploy in an emergency.

A finding like this must be taken seriously and should be checked promptly.

Which vehicles is the 77960-T3L-C020-M4 fitted in?

The 77960-T3L-C020-M4 is fitted in these vehicles: Honda Accord 10th generation (2017-2024) and 11th generation (from 2023).

The following models are assigned to this unit:

• Honda Accord 10th generation (2017-2024)
• Honda Accord 11th generation (from 2023)

Compare the part number on the label of the removed unit with this page. This only confirms that it is the right unit. Have the fault memory read out beforehand, because only that result shows whether the control unit itself 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-SDA-L814-M1, 77960-T3L-A012-M1, 77960-T3L-A01M1.

How does the repair of the 77960-T3L-C020-M4 work?

First have the fault memory read out and attach the log. Then disconnect the battery, only then remove the 77960-T3L-C020-M4, and create a repair order online. Afterwards pack the unit well and send it in.

The unit is examined on the test bench at Airbag24, defective components are replaced, the crash data is cleared and a function test is carried out. Processing takes 3–4 working days as a rule, and this time covers only checking, repairing and testing.

Afterwards your own 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 77960-T3L-C020-M4 get to Airbag24?

You send the 77960-T3L-C020-M4 as a parcel or book a UPS collection for an extra charge. After the repair Airbag24 sends the unit back to you by UPS.

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