- Re: bmw 520i battery drain Archived Message
- BMW 520i M54 2004 - Battery drain - Fixed # - Mark Murphy September 22, 2009, 9:01 pm
- Re: bmw 520i battery drain - andyhyoung September 22, 2009, 9:37 pm
- Re: bmw 520i battery drain - Pete Mutlow September 22, 2009, 10:23 pm
- Re: bmw 520i battery drain - Mark Murphy September 22, 2009, 10:39 pm
- Re: bmw 520i battery drain - Pete Mutlow September 23, 2009, 10:09 am
- Fixed # - Mark Murphy September 25, 2009, 9:08 pm
- Re: bmw 520i battery drain - Pete Mutlow September 23, 2009, 10:09 am
- Re: bmw 520i battery drain - Mark Murphy September 22, 2009, 10:39 pm
- Re: bmw 520i battery drain - Pete Mutlow September 22, 2009, 10:23 pm
- Re: bmw 520i battery drain - andyhyoung September 22, 2009, 9:37 pm
Posted by andyhyoung
on September 22, 2009, 9:37 pm, in reply to "bmw 520i battery drain"
Testing the smart charge system is a bit involved on these.The charge rate is controlled by the Dme engine management system.The small sense wire at the alternator runs to this ecu.I have found the only way to check these is to scope the wire and see if the signal alters with electrical load.Also you need to check the battery sense system.Behind the o/s/r light,above the battery,is a small 2-pin blue connector.Check this for water/corrosion damage.Also lift out the false floor where the spare wheel would normally sit and you will find a mini-power module.Again check this for water ingress.Lastly,you say it has had a "new" unit.Is this a genuine or pattern rebuild?Hope I have shed a bit of light on this for you.
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