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Old 07-20-2019, 12:33 AM
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wpoll wpoll is offline
Join Date: Sep 2015
Location: South Island, New Zealand
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Originally Posted by Kingfisher View Post
Thanks much. My jumping B+ is connected to the alternator for sure cause it's getting alternator voltage, but I'm not sure if the battery cable is connected to the alternator via the jumping terminal. I'll do the jumping cable test first before anything else.
Another test you could try is a voltage drop test while cranking...

Using a multimeter, set to 20 volt range, connect the negaitve (black) lead to the B+ jump terminal and the positive lead (red) to the B+ battery terminal. Use any long wire to extend one of the leads - this wire wil carry almost zero current so it doesn't need to be a big wire.

Inital reading should be close to zero volts. Now crank the car and read the voltage that appears of the meter while cranking. Anything more than a volt or two indicates that the wiring from the battery to the jump terminal is faulty somewhere.
2005 BMW X5 3.0d (b 02/05)
2001 BMW F650GS Dakar (b 06/01)
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