URGENT: 2010 BMW X5 35d No communication all powertrain modules (DDE, EGS, DSC, etc)

[andrewwynn]

Wiring fault can make for codes unrelated but if you get a code especially one that doesn't show MIL, but your just shook a particular harness you just located the location of the fault

[Diesel Spectre]

Try to isolate the modules with faults to a particular “shared” point. In other words, look at the wiring and try to find something common between the shut down modules. Either a particular section of wiring harness or possibly a ground. Although not the same symptoms I had last year, I spent over a month trying to comb through parasitic draws and such. Grounds showed no voltage drop with a dmm but as soon as I tried to start it, it would shut completely down. Acted like a dead battery and I was pulling codes for a bunch of modules related to the drivetrain. Turned out to be the ground from chassis to engine. All the modules grounded to the chassis had access after a start attempt while all the modules grounded through the engine ground were incommunicado. Replaced the appropriate ground and all was well. The thing that threw a wrench in it for me was I was also having an issue with the ground to the exhaust. This caused some symptoms that didn’t align with what finally was the actual issue. Be diligent but start with the basics. Don’t go looking for 8 legged zebras if it’s likely horses you hear. Sometimes it’s just two horses.