electrical issues

[jaffar]

Hi all

Two days ago, my airbag dash light came on. I was not too worried, as I already heard this may be a "common issue". After I got to work and the car sat for a few hours, the light even went away. It came back after a few kilometers though.

While looking for a service with a diagnostic computer, things evolved:

- the radio turns off and on by itself (also does not turn off when I stop and take out the key, or does not turn on when I start the engine)
- the interior light turns on and off by itself, or just sort of blinks, like someone is playing with its wires
- the steering wheel controls for the radio stop working randomly (but the gearshift paddles still work)
- the wipers/washers work from time to time
- the horn works from time to time
etc.

Basically all modules have gone insane.
One time, the engine would not start. It was rotating but not starting. Took a couple of minutes of trying to get it running.

I went to a service and looked at the errors - the first one was the airbag module complaining about undervoltage.
They cleared all the errors, but they come back as soon as I start the engine.
They said it's a "common problem" with the Z4 and proposed to check the airbag module for bad contacts. They said the airbag module is acting up and is sending "bad signals" over the KCAN and is making all other modules crazy.

They also checked the battery with a tool and said it's in good shape. Voltage with engine running is 14.07V so the alternator/charging relay seems ok, too.

I took out the battery for a few hours, nothing changes. I also tried to charge it overnight, just to be sure - does not help.

Any suggestions are welcome.
Thank you