First if I'm typing this from a cell phone. So forgive the errors please. And I'm going off the info I remember from him and me talking. 

Co worker had a 95 12v auto. He's had in the shop for a few months. 

Od quits. Tech quits. No od. 

They have put new ECM in a few times. 

And have traded every wire that should cause some of the issues.

I told him to check for AC noise on the alternator. And a bad ground. He tells me it's a new alternator. But that doesn't mean much. 

 

Thoughts and suggestions? 

Ok 1995 12V is only a PCM there isn't any ECM on those trucks.

 

OD is just a signal wire for ground. In other words OD is controlled by the PCM which switch on and off the ground wire. The 12V supply comes from the transmission relay which provides power to the solenoids in the pan.