Airbag Warning Light - Control Module or wiring?

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DogWagen
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Airbag Warning Light - Control Module or wiring?

Post by DogWagen » Sun Jan 08, 2023 7:57 pm

When I took the B3s out this afternoon, I had the Airbag waring light stay on.

It's done this before occasionally but usually goes away when the car is switched off and on again. A check of the fault codes when I got home showed 04 Airbag, passenger, stage 1 and F0 Internal control unit fault. I erased the fault codes started up and now have the F0 code and 73 Seat-Backrest locking, driver - the passenger airbag fault has miraculously cleared...!

Has anyone else experienced this sort of fault before or can offer a view on where to look? Am thinking that the Airbag Control Module could be at fault - seems to throw faults with low voltages - but am thinking the underseat connectors/wiring could be worth a check for damage/corrosion.

Any suggestions would be appreciated.

Mike

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Charles
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Re: Airbag Warning Light - Control Module or wiring?

Post by Charles » Mon Jan 09, 2023 9:38 am

Potentially a whole host of areas to look at but, if it is always the same unit then that should help narrow the field.

We get an occasional airbag warning in the Espace which we have traced to a dry connection to the driver's seat side bag - so checking connections before changing hardware might be a sensible way to go in the first instance.

However, just a random thought, but when did you last change the battery and/or give the car a decent run to properly charge it up? From my experience, 6-7 years is about the lifespan of the battery on the E46 and reduced voltages as a result can play havoc with all sorts of electronic elements of the car.
Charles
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B3S Touring (49/116) - been to the moon and now on the way back!
Renault Grand Espace - not mine but the wife's!

DogWagen
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Re: Airbag Warning Light - Control Module or wiring?

Post by DogWagen » Mon Jan 09, 2023 7:48 pm

Thanks for the input Charles,

The battery was changed in Sept 2020 (Genuine BMW) and had a recondition via C-Tek early in 2022 (just put it on for a periodic refresh today). I take the car out at least every month for a motorway/A-road run so hopefully the voltage/charge is OK.

I had a look at the Control Unit socket & plug - all clean although there was some grot on the hazard/locking switch connector when I took the rear console out. Have yet to find the airbag connector (think it's underneath the bag) but am also wondering if there's an earth fault. Would anyone know whether there are more earths other than in the electronics box under the bonnet?

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