SLOW BATTERY DRAIN

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Wil
Posts: 45
Joined: Thu Apr 30, 2009 6:27 am
Location: Chappaqua, NY

Post by Wil »

After a few months chasing this slow battery draw , I finally discover and fixed the problem.
I will like to share my experience, may be it will be helpful to somebody with the same issue.
As the advised given by other nice forum members, I started by removing the positive connector from battery and connecting the amp meter (set to read milliamps 20 or 200) I had over 190 milliamps where I should have under 10.
Keeping the amp meter connected I started to pull fuses and relays until fund the one that was related to the draw. That was the one feeding the glove compartment,interior light, clock,trunk light and power to lock motors.Disconnecting one at the time I isolated the problem to the power locks.
I also notice that every time the locks were energized they will make a click at the drivers door.
Asking other members I was told that to be normal (later I found that not to be normal).
The power locks get power from harness going by the left front speaker, disconnecting that I was able to stop the draw.
Now that harness has four wires ,red and brown feed the drivers lock motor, and blue and white take power from drivers lock motor to the other three doors.
Disconnecting the blue and white,but leaving the brown and red connected I still had the draw so that isolated the problem to the driver door lock motor unit.
Following FAQ open the unit to found that one of the three contacts had a broken spring, leaving the unit always drawing power.
Now there is no more click and no more slow battery drain, only 5 milliamps draw at the terminal :D
Thank you for all your help
Wil
1978 520 - 1980 528i
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1st 5er
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Post by 1st 5er »

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Sherman

TexFest LSB&F V

95 525iT (Her DD)
92 ///M5 (????)
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79 528i (1st 5er)
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Blaise
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Post by Blaise »

Great job in diagnosing the problem properly. Thanks for sharing.
1977 BMW 530i
1973 R75/5 BMW (motorcycle)
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Lenny D.
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Post by Lenny D. »

"I also notice that every time the locks were energized they will make a click at the drivers door.
Asking other members I was told that to be normal (later I found that not to be normal)."

I believe it was me who told you that.

My car has functioned this way since I bought it in '82. Every time the the locks are actuated there is a delayed 'click'.

I have no battery drain.

I believe I also told you there is an emergency release function to the power locks that can fail and remain energized, I believe the FAQ addresses that.

Congratulations on solving your problem.
HTH

'80 528i
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Wil
Posts: 45
Joined: Thu Apr 30, 2009 6:27 am
Location: Chappaqua, NY

Post by Wil »

" I believe it was me who told you that.

My car has functioned this way since I bought it in '82. Every time the the locks are actuated there is a delayed 'click'.

I have no battery drain.

I believe I also told you there is an emergency release function to the power locks that can fail and remain energized, I believe the FAQ addresses that. "

Dear Lenny,

I will like to thank you for all your help , it was very much appreciated.

I didn't want to by any means criticized your advise or complaint about it, I just wanted to clarified and tell so others can learn, just like you said.

Now that you explained ,my click and your click were different.

I was getting my click every time I installed the fuse on the fuse box, or I connected the terminal to the battery.

You were talking about the one when turning the door key,

Anyway thanks again to everybody

Cheers

Wil

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1978 520 - 1980 528i
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