Airbag control unit with part number 985103006R

What does the airbag control unit 985103006R do?

The airbag control unit 985103006R is the central control unit of the restraint system (SRS) for Smart. It evaluates the crash sensors and decides in an accident which airbags and seatbelt pretensioners fire. After an accident it stores crash data and locks itself.

The control unit monitors the restraint technology continuously. It checks the sensors, the firing circuits and the connections to the restraint devices, so that the system is ready in an emergency.

It stores detected deviations in the fault memory. They are displayed via the airbag warning light in the instrument cluster, and only the repair lifts the lock after an accident.

Why does the control unit 985103006R fail?

The most common cause is crash data stored after an accident, even if no airbag was triggered. A normal diagnostic tool does not make it disappear. Aged components, cold solder joints, moisture and corrosion at the plugs, and voltage peaks are also possible causes.

The fact that crash data can be erased means for you: Airbag24 removes it during the repair. Until then it remains in the unit.

Aged electronics are a cause in their own right, as are solder joints that give way over time. Moisture and corrosion attack the plugs, and voltage peaks, for example from a weak battery or a jump start, put strain on the unit.

Only the inspection shows which cause is present in your unit.

How can you tell that the 985103006R is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently, an error message appears in the instrument cluster, the diagnostic tool gets no connection to the control unit, and the fault memory cannot be cleared.

Typical signs are:

• airbag warning light permanently or intermittently on
• error message in the instrument cluster
• no connection between the diagnostic tool and the control unit
• fault memory cannot be cleared

In an emergency, airbags and seatbelt pretensioners may then fail to trigger. Please have the finding checked promptly.

Which vehicles is the 985103006R fitted in?

The control unit 985103006R is fitted in these vehicles: Smart Fortwo C453 (2014-2024).

For this part number we have the following models on record:

• Smart Fortwo C453 (2014-2024)

Match the part number on the label of the removed unit against this page. This only confirms that it is 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 the cause.

For the same vehicles, we also repair control units with the part numbers A453 901 89 00, A4539001702, A4539017400.

How does the repair of the 985103006R work?

First have the fault memory read out and enclose the log. Then disconnect the battery and remove the control unit 985103006R. Next, create a repair order online and send the unit in well packed. Processing at Airbag24 usually takes 3–4 working days.

The sequence is fixed for safety reasons. The battery is disconnected only after the log is available, and removal comes last.

At Airbag24 the unit is checked on the test bench, defective components are renewed and the crash data is erased. A function test completes the work, after which your own unit is 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 985103006R get to Airbag24?

You send the control unit 985103006R as a parcel or book a UPS collection for an extra charge. After the repair Airbag24 returns it to you by UPS.

The printed repair order goes into the parcel. Pack the unit shockproof so that it arrives undamaged.