Battery drains while car is running, new alternator and voltage regulator

2001 MERCEDES BENZ SLK320
131,000 MILES • V6 • 2WD • AUTOMATIC
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DUHOMME
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  • 1 POST
Battery charge warning light came, then systems went offline until car shut off. The alternator and voltage regulator test fine. New ones do as well. Battery replaced. Problem still there.
Dec 9, 2019 at 2:54 PM
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SCGRANTURISMO
  • ASE Certified Mechanic
  • 4,897 POSTS
  • ASE Certified Mechanic
Hello,

This could be a problem with the wiring from the alternator to the battery. In the diagrams down below I have included the wiring diagram of the charging circuit for your vehicle and a guide on how to find opens in automotive electrical circuits and how to find unwanted resistance in an automotive circuit using voltage drop. You will need to use a Digital Multi-meter [DMM] to go through these guides, so here is a link below explaining how to use one below, if needed:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Please go through these guides and test the highlighted wires in the wiring diagram and get back to us with what you find out. We can go from there.

Thanks,
Alex
2CarPros
Dec 9, 2019 at 10:08 PM
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