Airbag diagnostics on Bentley Arnage and RR Silver Seraph

[SGERAT]

Hi Guys,

After looking for info during some days I find this forum. At first, I want to introduce myself, I'm a technician from Spain, so if anybody need help with any truck or car contact me and I will try to help .

I find this forum because I have a big problem with an airbag light on in a Silver Seraph, the light comes without reason, when we have finished the works in the car and after a road test without any problem ( the works don't involve nothing about the airbag so I think it's an sporadic fault ). The problem I have is that my diagnostic tool ( TEXA IDC4 ) don't works with RR or Bentley ( I can connect to abs, engine and transmission choosing BMW in the tool, but this don't work with the airbag.

After achieving the service manual and the wiring schematics I have seen than the airbag module is connected to a different bus line than the engine,abs,and transmission modules, so maybe because it I can't connect with my diagnostic tool ( because probably it try to connect with the same line than the others modules ).

I have the temptation to connect manually the line where the airbag is to my diagnosis tool and try to connect it like if it were an airbag module of a BMW, but how I don't know what protocol is using the bus where the airbag is have fear to break something.

So if you can tell me what diagnostic tool works with these cars which allow to reset the airbag fault codes I'll be much obliged with you.

Regards and thanks in advance

[buyer&seller]

First of all I am not a mechanic and do not understand the technical stuff but I have bought and sold loads of these cars (Seraph & Arnage) and have had to pick up the bill for getting them fixed.

The air bag light seems to be a common occurrence and the last one I had with a problem was due to the printed circuit in the seat being faulty. Bentley used to supply this part but now want to fit the part themselves at the factory to ensure it's done correctly, which is fine but they want to charge a fortune, around £1000 if I recall correctly. So I managed to get the part from a BMW dealer, the part number is 65776940422, for about £150 and get a very competent technician to fit it for me.

I hope this help steer you in the right direction.

[SGERAT]

Thanks for your reply friend,

The owner of the car told me that the airbag light show in the cluster a lot of times during years, and his mechanic only need to connect the diagnostic tool and erase the fault. So probably the fault I have isn't active, but without the proper tool I can't read or erase the fault code. I'm searching because the mechanic who works in this car in the past isn't a RR service ( in fact, the nearest service is at 400 km of distance ) so I think that should be a non official diagnostic tool that can connect to the airbag system in these cars. The hard is to find it..

Regarding the presence detector on the copilot seat, it's easy to cheat the system with a pair of resistances, but the fact that if the airbag light goes on it don't turn off until you clear the code with the diagnostic tool is a misfortune.