Good news and bad news.

I believe you can determine if the ground strap/s are the problem.

Measure the voltage from the block to chassis with the engine running. It should be under 0.5v. If you have more especially if over 1v, the cable/s are shot.

There are 2-3 cables: bare ground straps (Earth strap) and an alternator ground cable.

The bad news: have to remove the skid plate to replace.

One is apparently under the ac compressor I've not located the other on the E53/M54 (my engine).

Measure the voltage to determine if the cable is bad. You can use a jumper cable to ground the block and if the problems fade you've found the problem


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2011 E70 • N55 (me)
2012 E70 • N63 (wife)