hey guys, this is my lady's 318i. recently she had started to show this issue and i first taught it had something to do with the alt.
what happens is when she hits her brakes the tach jumps up(car doesn't rev)
and the radio will cut out.
Also if she uses her blinker the radio shuts off.
when she gets home the battery is about dead.
I checked and I'm not showing any Key off shorts, from what I can tell
i cleaned and retightened the central ground near the brake pedal
also change out the battery with the know good one from my e21 and see if its the battery
I had the alt tested at the battery and found that with the car off battery was at 12.56vts, but with the car running it went down to 12.05vts. I then replaced the engine ground strap, valve cover ground strap, battery ground strap and positive battery lead.
I then tried the test again from the battery and found the same results, this time I move the tester to the alt. with the pos at the large lead and the ground on the strut tower while the car was running I was still getting the same low voltage at 12vts. I pulled the alt and had it bench tested and found that it was putting 14vts out on the bench. I also found that the ground to the alt was pretty green and aged. I replaced that, but before I did I had them bench test it with using the old nasty ground strap as a ground hook up and the alt still put out 14vts. I replaced the ground strap anyways.
i have found that my battery light won't come on with key in the on position, I checked and it has a know good bulb in its socket.
the two thermals on the alt one the large one has pos from the battery but the small next to it was grounded, which I feel should be positive. I believe this feeds the battery light, and if so does it supply the ground or positive
i tried to apply direct POS and NEG to the small wire coming from behind the alt which im assuming is the battery light(?) with the light not coming on.
any ideas?
-does battery light need to be functioning for it to properly charge, i know with some cars it does (old air cooled vws)
-are both thermals on the alt suppose to be putting off a POS charge?
1 im getting POS (duh, its connected to the battery haha)
but 2 im getting NEG, so my question is that normal
what happens is when she hits her brakes the tach jumps up(car doesn't rev)
and the radio will cut out.
Also if she uses her blinker the radio shuts off.
when she gets home the battery is about dead.
I checked and I'm not showing any Key off shorts, from what I can tell
i cleaned and retightened the central ground near the brake pedal
also change out the battery with the know good one from my e21 and see if its the battery
I had the alt tested at the battery and found that with the car off battery was at 12.56vts, but with the car running it went down to 12.05vts. I then replaced the engine ground strap, valve cover ground strap, battery ground strap and positive battery lead.
I then tried the test again from the battery and found the same results, this time I move the tester to the alt. with the pos at the large lead and the ground on the strut tower while the car was running I was still getting the same low voltage at 12vts. I pulled the alt and had it bench tested and found that it was putting 14vts out on the bench. I also found that the ground to the alt was pretty green and aged. I replaced that, but before I did I had them bench test it with using the old nasty ground strap as a ground hook up and the alt still put out 14vts. I replaced the ground strap anyways.
i have found that my battery light won't come on with key in the on position, I checked and it has a know good bulb in its socket.
the two thermals on the alt one the large one has pos from the battery but the small next to it was grounded, which I feel should be positive. I believe this feeds the battery light, and if so does it supply the ground or positive
i tried to apply direct POS and NEG to the small wire coming from behind the alt which im assuming is the battery light(?) with the light not coming on.
any ideas?
-does battery light need to be functioning for it to properly charge, i know with some cars it does (old air cooled vws)
-are both thermals on the alt suppose to be putting off a POS charge?
1 im getting POS (duh, its connected to the battery haha)
but 2 im getting NEG, so my question is that normal
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