Need help 88 M5-battery light on the dash stays on

Ok I needs some help here. Sometimes when I turn the car off the battery light on the dash stays on. When this happens if I let the car sit for more than two days the battery will go dead. When I turn the car off and the battery light goes out the car can sit for weeks no problems. Here is what I have done so far. Replaced the battery, I pulled each fuse out one at a time hoping to isolate the system that is causing the problem and I change the electric antenna with a manual one. This use to happen only once and a while, now it happens almost all the time.

Hope you can help

Thanks
Chris

[Drake]

Pull out the battery light if all else fails. Beats having a dead battery all the time.

[Chris]

I've given wrong advice before so please take with a grain of salt.

Could be a bad diode in the alternator. Disconnect one of the wires on the back of the alternator while the light is on and it should turn it off... not sure which wire on the 88 M5. Maybe look for a small gauge red one?

If it turns the light off, then that's your problem and solution. Replace the alternator and you should be fine.

Also check to see that your batter cable connections are free of corrosion.

Hope that helps.

[kowalski]

could be your ignition, the relay is what gives you power and if the power isn't being cut to the relay then you will have constant power. could be a loose connection in the ignition. if you pull the battery light your alt. won't work because that light is hooked up to the excitor wire which activates the alt.

Everyone Thanks for the tips. I will check the alternator out this weekend.

Chris

Originally Posted by cacostar Everyone Thanks for the tips. I will check the alternator out this weekend. Chris

I wanted to thank everyone. I turn out to be the alternator.