Airbag control unit with part number 985100778R

What does the airbag control unit 985100778R do?

The 985100778R is the airbag control unit that centrally controls the restraint systems (SRS) of Renault. From the crash sensors it reads the situation and, in a crash, decides within milliseconds on the airbags and seatbelt pretensioners. After an accident it stores crash data and locks itself.

The system is monitored by the unit throughout; a detected fault is reported via the airbag warning light in the instrument cluster.

The task is therefore clearly defined: triggering in an emergency and monitoring in everyday driving.

Why does the control unit 985100778R fail?

The most common cause is crash data stored after an accident, even without an airbag having been triggered; a normal diagnostic tool does not erase it. Other possible causes, in brief, are ageing electronics, cold solder joints, moisture and corrosion, and voltage spikes.

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

Some of these causes cannot be reliably identified from the outside.

Examination of the unit shows which cause is present.

How can you tell that the 985100778R is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently, and a fault message is shown in the instrument cluster. The diagnostic tool finds no connection to the control unit, and a fault memory cannot be cleared.

As long as the control unit is faulty, airbags and seatbelt pretensioners may not be able to trigger in an emergency. A warning sign like this must therefore not be ignored.

The warning light shows the defect clearly, so it cannot be overlooked.

Which vehicles is the 985100778R fitted in?

The 985100778R is fitted in these vehicles: Renault Master III (2010-2024).

The vehicles at a glance:

• Renault Master III (2010-2024)

Compare the part number on the label of the removed unit with this page; that only confirms that it is the right unit. Also have the fault memory read out beforehand, because only the log shows whether the control unit is defective or whether a plug or a cable is the cause.

For the same vehicles, we also repair control units with the part numbers 611136500, 8200942209A, 8201448823, 8201448824, 985105091R, 985106290R.

How does the repair of the 985100778R work?

Have the fault memory read out, attach the log, then disconnect the battery; only after that remove the control unit. Then create a repair order online and send in the well-packed unit. Airbag24 checks it on the test bench, repairs defective components, erases stored crash data and carries out a function test; this usually takes 3–4 working days.

Afterwards your own unit comes 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 985100778R get to Airbag24?

You send the unit as a parcel or book a UPS collection for an extra charge. Airbag24 sends it back to you via UPS after the repair.

Pack the unit so that it is shock-resistant and enclose the printed repair order.