GMC Troubleshooting Questions? Ask a Mechanic for Answers
I am sorry your having this problem
as soon as you clear the codes they come right back ?
do you have a multi meter on hand ?
can you idle the truck and see if the fuse called IGN0 in the drivers side inside fuse box shows 12 volts at both sides of that fuse testing it in place through the little openings in the tops of that fuse ?
do you have any access to a scan tool that has functions on the scan tool to command on and off the shift solenoids and tcc solenoid ?
and to be clear this has a 4L80 in it now ? and this swap used to have no codes or check engine light and shift fine after the swap ?
did this engine and transmission swap ever shift correctly and NOT have any codes ?
which computer are you using with this swap ? the one from the swap or the original one ?
we also need to see if the TCC and the 3-2 shift solenoid is being activated with a scan tool turning them on and off and see if the ground signal is present at the connector at the transmission
with both those codes and 12 volts at the pink transmission wire we are either not getting the 12 volts in the internal wiring harness to the solenoids or the computer is not sending the ground to turn on either the tcc or the 3-2 shift solenoid but from the sounds of this since the transmission seems to go into lock up there is a chance those ground signal wires are shorting to ground causing this lock up at 7 MPH
i have a clue thank you when you have a transplant like this there is NO exact flow chart to find this problem we have to make sure on a lot of things
like : which computer are you using
: can we command on and off the tcc and the 3-2 solenoid ?
is the computer grounding the correct wires for this swap over ?