Hi Dave,

We were typing at the same time, I guess.



This shows how the fuel injection system gets its ground references. ECU-17 is the power ground, and the reference for the relay driver transistor on the hybrid.



To see the actual wire you'd need to follow it back under the vinyl sleeving where the splices are made. Folks have reported corrosion problems with the splice, but I doubt a poor ground is to blame in this thread about 951's being killed.

One other cause I remember learning was a mechanic who was newly enamored with a "power probe" which in knowledgeable hands can be a useful diagnostic tool for energizing circuits. I emphasize knowledgeable because if such a tool applied 12V to pin 20 on the ECU, it wouldn't matter what else was wrong, the part on the hybrid would be destroyed. I'm familiar with hybrid microcircuits, especially from this era, and there is no field repair of them I'd trust in a car.

--
Art Benstein near Baltimore

Wise men speak because they have something to say; fools, because they have to say something -Plato