BMW Electrical problems

Wed Dec 29, 2010 7:23 pm

Well here's the story, alternator was restored there, and put back on the car and a different battery put in the car. Pretty much the same thing is happening as when I first restored alternator and battery. Jump it off another car, car starts running again, drive it a very short distance, and you know the car is ready to cut out as wipers start going slowly and lights dim inside car then eventually it cuts out and stops.
If the alternator and battery have been restored/changed, does anyone know what else the problem could be?

Thu Dec 30, 2010 2:10 am

If the battery lite does not come on as you turn the key to start then the alternator possibly wont charge. Not knowing the year of your car makes it hard to help you. put that info in your signature profile for future reference.

Fri Dec 31, 2010 7:57 pm

The battery light doesn't come on whatsoever when I turn the key, what's the significance of this?

Fri Dec 31, 2010 8:14 pm

Then something sounds like it's missing. Is there a good earth connection between the engine and the bodywork? What about the other dash lights? What happens if you put a jump lead from the engine to a suitable earth connection on the bodywork and then turn on the ignition? Does the battery light illuminate then?

Fri Dec 31, 2010 9:53 pm

A second test: Connect a wire between the SMALLEST terminal at the alternator (blue wire) to earth on the body with the ignition on. Does the battery warning light come on?
Don't attempt to start the car with the wire in place!

Sat Jan 01, 2011 12:38 am

With a missing or burnt out battery red light bulb in the dash cluster the alternator does not energize. That depends on the year of the car. Wheres the info on the car?

Mon Jan 03, 2011 3:42 pm

sorry, its a 1989 318i. does that help. Are you saying the fault oculd be because of a faulty battery dash light? Thanks

Mon Jan 03, 2011 7:15 pm

gazzaraggi wrote:sorry, its a 1989 318i. does that help. Are you saying the fault oculd be because of a faulty battery dash light? Thanks

I doubt if it's quite that simple, but I do expect that when the light works, then so will the whole problem be solved.
Some versions of the 318i have the alternator mounted on rubber bushes, and needs an earth strap to bypass these electrically. Is yours one of these, and does it have the strap fitted?