Bentley Azure Cabriolet airbag control unit repair

What is a Bentley Azure Cabriolet airbag control unit?

The airbag control unit is the nerve centre of the Bentley Azure Cabriolet restraint system (SRS): it processes the signals from the crash sensors and, in an emergency, decides within milliseconds whether and which airbags and seatbelt pretensioners fire. At the same time, it continuously checks that the whole system is working properly.

The sensors detect deceleration and impact and pass these values on to the control unit, which uses them to decide whether to deploy. This unit is fitted in the Bentley Azure Cabriolet (1995 to 2003) and works unobtrusively in the background while you drive.

If something is wrong in the system, the unit alerts you with the airbag warning light. If there has been an accident, it stores the crash data and locks itself.

Why is the Bentley Azure Cabriolet airbag control unit defective?

The cause is usually crash data left in the Bentley Azure Cabriolet airbag control unit by an accident, even if no airbag deployed. Other possible causes are ageing of the electronics, cold solder joints, moisture and corrosion on the connectors, or voltage spikes.

A standard diagnostic tool cannot remove stored crash data. The unit therefore keeps reporting a fault, even though the airbags, seatbelt pretensioners and wiring may be perfectly intact.

Voltage spikes can occur when the battery is weak or when the car is jump-started. If moisture gets into the vehicle, the contacts of the plug connections often suffer. On top of that comes normal wear: solder joints and components age over the years.

You will notice it when the airbag warning light stays on permanently, the fault memory cannot be cleared, or the diagnostic tool cannot connect to the control unit at all.

Common error codes for Bentley Azure Cabriolet airbag control unit repair

The codes that occur here concern the circuits that fire the seatbelt pretensioners and belt force limiters. They report that the activation or resistance of one of these circuits is not within the expected range.

The following codes occur on this vehicle, among others:

• B130474 → Seatbelt pretensioner front left, activation deviates
• B130574 → Seatbelt pretensioner front right, activation deviates
• 00654 → Seatbelt pretensioner driver side, resistance out of range
• 00655 → Seatbelt pretensioner passenger side, resistance out of range
• 01740 → Belt force limiter driver side, resistance out of range
• 01741 → Belt force limiter passenger side, resistance out of range

Error codes are read out with a diagnostic tool. A single code cannot tell you reliably whether the control unit is really defective, as a connector, a wire or an airbag module could just as well be the cause. Only an inspection shows where the fault lies.

What part numbers are available for the Bentley Azure Cabriolet airbag control unit repair?

You will find the part number on the label of the control unit; it defines its exact version. Because equipment and year of manufacture lead to different numbers, it should not be missing from any repair order for the Bentley Azure Cabriolet airbag control unit.

We currently have no part numbers on file for this vehicle. Please note the number directly on the removed unit and enter it in the repair order, so that your unit is matched to the correct version.

Whether there is a defect only becomes clear when the fault memory is read out or when the unit is inspected in our workshop. Here is how to proceed: first have the memory read out, then disconnect the battery from the vehicle electrical system and remove the control unit. After that, create a repair order online and send in the unit. At Airbag24, inspecting, repairing and testing usually take 3–4 working days.

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.