[V8] ECU grounding, etc.

[Buchholz, Steven]

... the wiring diagram indicates that there is some ground point connections internal to the Motronic harness the diagram calls it point 139 and it is the grounds for the sensors.  If this goes bad it may affect all the inputs to the ECU.  I don't see the Kostal connectors shown ... they have to be ... I must have missed them.  I'd recommend the divide and conquer technique, verify the harness from the ECU to the Kostal connectors, and then from there to the engine.  You will probably have to unwrap the loom and try to find the internal connections to find the problem.  

You might want to see if you can scare up a replacement loom ... at least for testing purposes.  The loom for the engine is actually fairly easily extricated ... but then it does go all over the engine proper ... 

Steve B
San José, CA (USA)

... facing a similar issue with the operation of the rear speakers on my car's Bose system ... 
> 
> No change... this brings us to yesterday.  Test light and multimeter in
> hand, I went through the manual's check process for ECT sensor (G62), O2
> sensor, and MAF sensor -- all failed the checkout, with all blaming the
> ECU or its wiring.
> 
> So I pulled the ECU harness connector away and did two checks before it
> was time to call it quits:
> + ECU voltage supply check asks to confirm ground at terminals 10, 14,
> 19, 24, and 54 of the harness connector ---  All were good except at 54.
> + I also picked back up on the MAF sensor check procedure, which was
> asking to verify continuity between ECU harness connector pins 19 & 37.
> No good.  Blames an apparent short between ecu pin 37 and terminal #5 of
> the MAF sensor connector.  So far no luck finding a short...
> 
> So the upshot is: how does terminal #54 of the ecu harness connector get
> its ground?  Any other thoughts?