Electrical issues from battery? (2008 Mini Cooper S Convertible)
Hi all. I've got a 2008 Mini Cooper S convertible which has suffered electrical gremlins for a while. It starts fine but during driving will randomly start playing up, potentially related to bumps in the road. This causes:
- Turn signal / indicator warning light in the cabin to stay on even when the stalk and probably outside light is off
- Airbag warning light to come on
- Stereo to lose responsiveness e.g. volume changes not registered until it rights itself many seconds later
- Clock/miles display dims randomly
- Cd player display dims randomly
- Cd player randomly stops and restarts
- Seatbelt warning light comes on when both/one passenger seated with belt fastened
- Seatbelt warning sound dings when seatbelts fastened, then stops randomly
- Yellow brake warning light (exclamation within trial within arrowed circle)
- Yellow 2 person passenger airbag off indicator above rear view mirror
- Indicators staying on as usual BUT also timing out while turned on and waiting for the traffic light to turn green
I've taken it to our local garage, who had it for a total of about 2 weeks & were commuting to & from work with it - with me paying for petrol - so they could diagnose. Ended up changing the central computing unit in the dash (with speedo) and were considering changing the other dash computing element (I forget the name), they may have actually done that. Their diagnostics showed the K-Bus interface was acting normally. Conclusion is that we ostensibly owe the garage ~$1000 for parts and work, but the problems remains. I've told the garage this and they haven't replied, so we're at an impasse. I'm not rushing to give them $1000 to have solved nothing, and they're evidently ok to write off the money and time they've spent and lose us as customers.
But I'm still in the same spot. I discussed this with my uncle, a car guy, who said it sounded like a battery issue: either battery or cables not housed or connected well, or the earth cable was shorting somewhere along its run, causing the battery signal to the computers to flicker intermittently and play havoc with the electronics. He advised checking the leads, ensuring the battery connectors we on firmly, maybe with vaseline, and tracing the run of the earth wire. I checked that the battery leads are connected firmly but haven't yet done vaseline, and can't seem to check the run of the cable because it's in the boot/trunk and the cables almost immediately burrow into custom-made holes and disappear.
Does anyone think that my uncle's explanation sounds reasonable? Can anyone advise of how I can check to fix this issue given that I don't seem to be able to access the battery cables other than the first tiny run before they disappear?
THANK YOU in advance, for any ideas.