Join Date: Dec 2005
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Any wire that is bolted to the body is an earth.There maybe some hidden around under the dash,but I'd start under the bonnet.This is where they are more likely to corrode and give problems.The heater motor and wipers MAY earth in the same spot,and this would explian your symptoms,but this is only a guess!
Just remove any wire that is bolted to the body and make sure the connections are clean and that a good connection is possible to the body.Any 'greening' of connections is a tell tale sign.Also try the earth lead to the wipermotor body first.
Good luck,and get back to us if you're successful(or not!).
I'd rather push my Alfa than drive a BMW....
Currently in Lagdti's garage:
2004 Saab 9-5 HOT Aero and a 2001 Audi A3 1.8 Turbo