The issue I'm having has been going on for about 2 months now.  Started out as a bad valve body. Pull the truck down in gear it would **** off I replaced the VB with a revmax HD and a triple disc converter with a low stall.  Fixed that issue. But then about a week after while cleaning and prepping for paint I lost all power with symptoms of limp mode.  Did some looking and codes led to low 5 v supply.  Probes the wire and walls no 5v reference from the ecm.  My question is is there anywhere else on the harness I can get a 5 volt feed to run to the map and iat to see if it fixed the problem before dropping the money on a new ecm.  The truck spins over more now then it used to to crank about 5-8 seconds then fires up and idled fine.  Will rev fine also. But I guess with it not reading any map pressure it won't continue to fuel if you try to drive it. It continues and basically lags into 2,3 and then peters out from there  I'm not one to throw parts. I have checked the drivers side battery try for the ground there and the wire coming off the ecm itself. Both seemed good. 

What codes do you have? Did you compromise the 5v ref near the bulk head when messing with the trans? The 5v ref from the ecm feeds a ton of stuff on the engine side of things. A year of the truck would help as well.

Edited September 13, 20177 yr by jlbayes