I have been plagued with this problem for five years. Please help.
Battery voltage when ign off is now 12.2 volts but five years back was 12.7 volts.
Airbag Fuses 40 and 42 are intact
At ign switch position 1 and 2 and with car running the airbag warning light is always on.
Six years ago we bought the car wit no warning light showing. At first it was intermittent. Five years ago the car went back to seller garage who got/had the light switched off. This lasted 5 miles and it was on again - intermittent.
6 months later the BMW Main dealer tested the system with diagnostics and found no fault. Light was intermittent at that time. Credit to Halliwell Jones in Chester they didn't charge for this work and time they put in.
A year later with light always on the local specialist BMW dealer got the light turned off - it was always on at that time. This lasted for about 2 miles and cost 100 pounds.
I don't blame them too much for they put the time in to sort it. Next try they didn't charge for for but the light stayed on. I decided to find the fault myself but it is not easy to track down but I really need your help other wise a good BMW becomes scrap at the next MOT.
This is what I have:
The car is the facelift model with only one OBD11 diagnostic port - in the drivers side cubby hole top surface.
My new B800 srs scan and reset tool for BMW shows no fault. Initially reading FA pressing "enter" just gives the two short horizontal lines. No codes. (Just like the BMW main dealer said happened with his professional diagnostic equipment).
Someone has removed a plug under the drivers seat and soldered the black wires to the seat to the incoming lead (not sure if this is an airbag sensor or not).
A meter test on the passenger seat airbag sensor wires showed no ohms. I took this to be open circuit and bought and fitted a Techtronics passenger seat airbag sensor by pass unit.
This has made no difference. The light is still on in all three ign switch positions. Needless to say I have tried all combinations of switching ign and B800 scanner on and off as described in the scanner instructions
I am beginning to think that my next purchase will have to be an SRS ECU. and with no fault codes to work on I will have to go on buying the bits until I happen across the faulty unit. Can you help on this matter please?