Bill, I'm looking at the ECU pinout on line, as I don't have schematics, other than my Haynes (useless for this). So far haven't paid to download factory schematics, but I'm thinkin' about it!

From your message:

"31/50 power ground
31/51 signal ground
and the engine power and signal grounds
31/32 engine power ground
31/33 engine signal ground"

The first two you are referring to are the ECU connections for the grounds, yes?

And the last two are where they go to? On a '95 schematic i found the chassis and engine grounds noted, the last two? One is the ground by the right headlight, the other above the starter. Those didn't change in 96-97 and I'm familiar with them. Other functions are working, so don't think that's the problem.

On the pinout I have four ground notations at the box:
B28, signal ground (check to negative bat term) For switching purposes perhaps, like what I’m looking for?
A28, power ground control module—The ECM’s primary ground perhaps?
A13, power ground Maybe more switching???
A18, Ground (sensor) Common ground for sensors?

DS