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7 Series - E38 (1995 - 2001)

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Old 12-22-2012, 05:59 PM
jtschwarm jtschwarm is offline
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Location: Vancouver WA
Join Date: Oct 2012
Posts: 8
Mein Auto: 1997 750iL
That damn battery light!!

I've read the standard answer a number of times on this issue, but have yet to read a reply explaining alternate malfunctions other than the alternator. I'm pretty sure mine is good, but my light is on constantly. I'm getting a strong charge to the battery and have not encountered any consequences that would lead me to believe I am experiencing a failure. Is it possible that that the light is drawing power from another source? Or... I have considered the possibility that something may not have been plugged in properly when the new engine harness was recently installed, causing what might be a normally 'on' circuit to light the indicator in the dash?? Grasping, surely. I've been driving with the light on for nearly two months without issue and am reluctant to take it back for diagnostics as the bill for the last repair was extreme to say the least.
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Old 12-22-2012, 07:59 PM
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joyism5 joyism5 is offline
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Location: USA
Join Date: Jan 2011
Posts: 1,271
Mein Auto: '99 740IL, K75RT
Battery could be a reason. Not holding sufficient amps.

The red light on the cluster comes on if the voltage is below 1.5 V. Fluctuations like 00-02 should not trip the light, in the cluster.

Here is the charging diagram from 95 740. Yours it is almost same.

page 12 :

There is a diode in the cluster, probably that one went bad. Have you checked the fuses in the front box? Look in the diagram to find them.

You are not the first one reporting the red light on with a possible good battery & alternator. There was a TSB issued a while back, read post #26
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Old 12-23-2012, 11:02 PM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
Join Date: Mar 2008
Posts: 25,236
Mein Auto: 02 BMW 525i M54 auto 130K
If it were me, I'd test the alternator & battery and report the test results for analysis:
- DIY how to test a BMW battery & alternator
Please read the suggested threads and add value, either by pictures or by descriptions, so the next person stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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Old 12-25-2012, 08:03 PM
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BMWFatherFigure BMWFatherFigure is offline
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Location: Perth, Western Australia
Join Date: Aug 2012
Posts: 4,106
Mein Auto: E23;E32;E34;E38;R50;R55
Dont think joy5 has his/her head round battery light function theory. Test out everthing first. IE Battery voltage, charging voltage, earths, joints and cables..
Good - Fast - Cheap: Pick any two.
3 x E32 735iL (Alpine White, Glacier Blue & Kashmir Beige); 2 X E38 735iL (Oxford Green & Alpine White); E53 X5 4.4i (Pearl Beige); R50 Cooper; R55 Cooper Clubman (Both Pure Silver).
E38 Parts Car
E21 318i; E23 735i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i
I've just changed my wiper blades and now my reverse lights don't work. Should I change my fuel pump relay?
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