Hi,

Having problem with starting my car as battery charged 12.87V but at the jump start connection under the bonnet showing 2.89V.

I hadn't started my car in a few days so I thought it was just some odd battery drain when I checked it with a multimeter it was showing 2.89V (I know, really LOW) I have managed to use one of the NOCO boost devices to start my car under the bonnet and it works fine, once the car starts (I am thinking alternator should be ok).

I have looked at the diagram from Haynes manual and there is one single cable red positive going from the battery to the positive charging point under the bonnet. Not sure that can cause some issues.

All the modules under the spare wheel compartment are dry and no signs of moisture.

Has anyone had similar experience? I have looked at similar topics but can't find anything.

Thank you in advance


5 series Touring 08'

 

Seems like some wiring could be loose or broken. You really need to read the BMW-specific codes first though.

 

I am guessing bad ground. One of the grounding points is loose, corroded or disintegrated.

"When corrosion, loose connections or other types of resistance restrict a circuit, volts and amps both drop. If volts drop, amps drop too."
Fluke electrical automotive troubleshooting