Airbag control unit with part number 77960-T0N-Z720-M4

What does the airbag control unit 77960-T0N-Z720-M4 do?

The airbag control unit 77960-T0N-Z720-M4 is the SRS control unit for Honda. It reads the crash sensors, makes the decision in a crash within milliseconds on whether airbags and seatbelt pretensioners are triggered, and monitors the restraint system continuously. Detected faults are passed on via the airbag warning light.

The electronics must be ready for operation at all times, because the decision in a crash leaves no time for detours.

After an accident, the unit stores crash data and locks itself. The consequences of this lock are explained in the following sections.

Why does the control unit 77960-T0N-Z720-M4 fail?

Most often the cause is crash data stored in the control unit 77960-T0N-Z720-M4 after an accident, even if no airbag has deployed. A normal diagnostic tool cannot erase them. Other causes are aged components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes.

Crash data remain in the memory after the event, and reading out with a standard tool does not remove them. The fault memory therefore stays unchanged until the cause has been fixed.

The other causes affect the electronics themselves. Components age, solder joints can turn cold, and moisture attacks plug connections. Voltage spikes, for example from a weak battery or a jump start, put additional strain on the circuit.

How can you tell that the 77960-T0N-Z720-M4 is defective?

A defect on the 77960-T0N-Z720-M4 shows up as the airbag warning light in the instrument cluster, as an error message there, and as a fault memory that cannot be cleared. The diagnostic tool also gets no connection to the control unit.

In detail, these signs appear:

• The airbag warning light is on permanently or intermittently
• An error message appears in the instrument cluster
• The diagnostic tool cannot establish a connection to the control unit
• The fault memory cannot be cleared

Airbags and seatbelt pretensioners may then fail to deploy in an emergency. Have these signs checked promptly.

Which vehicles is the 77960-T0N-Z720-M4 fitted in?

The control unit 77960-T0N-Z720-M4 is fitted in this vehicle: Honda CR-V 4 RM (2012-2018).

The vehicles known to us for this unit:

• Honda CR-V 4 RM (2012-2018)

On the one hand, compare the part number on the label of the removed unit with this page; this only confirms that it is the right unit. On the other hand, have the fault memory read out beforehand. Only this result shows whether the control unit itself is defective or a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 77960-T0A-3070-M4, 77960-T0A-A012-M1, 77960-T0A-A013-M1, 77960-T0A-A210-M1, 77960-T0A-A212-M1, 77960-T0A-A230-M1.

How does the repair of the 77960-T0N-Z720-M4 work?

First you read out the fault memory and enclose the log. Then you disconnect the battery and only then remove the control unit 77960-T0N-Z720-M4; next you create a repair order online and send the unit in well packed.

Airbag24 checks the unit on the test bench, repairs defective components, erases stored crash data and carries out a function test. The unit is then returned to you.

Checking, repairing and function testing at Airbag24 usually take 3–4 working days. 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-T0N-Z720-M4 get to Airbag24?

You can send the control unit 77960-T0N-Z720-M4 as a parcel or have it collected by UPS for an extra charge. After the repair, Airbag24 returns it by UPS.

The printed repair order goes into the parcel, and you pack the unit shock-proof.