new to me 2002 gmc 1500hd, 6.0 i rebuilt the 4l80e and it worked great for 40 miles at up to 45mph. tried to go on the freeway and the torque converter wouldn't unlock. I suspected bad tcc solenoid even though it's brand new, but it reads 14.6 ohms and my volt meter seems to be telling me it's getting voltage and being commanded to turn on when it shouldn't be. must be either the transistor in the pcm died and is giving power when it shouldn't (gm decided this transistor should fire a whole lot to modulate tcc lockup pressure so the transistor's health is suspect to me) or it could be a break in the wire harness but i was gentle with it during the uninstall and reinstall of the tranny and if i broke the wire harness it shoulda failed immediately not 40 miles into the rebuilt and only once i tried to drive the freeway and commanded full tcc lockup for the first time in 2 years. (truck sat at previous owners for a year and i spent a year fixing). I grabbed a spare 0411 pcm from a junkyard 01 tahoe with a 5.3. im thinking of getting a vx-nano on christmas sale and using pcm hammer, see if i can pull the tune from the old pcm and flash the replacement with the stock tune to start with and see if that fixes my locked converter. it will unlock when i unplug the harness from the tranny and in reverse and it's a rebiult tc so it's not physicaly locked just electrically and hydraulically locked whenever the harness is plugged into the tranny. if anybody has any links to educate me more on this process, or advice to respond here i really appreciate your time. I need to get a second person and some wire to voltmeter test my harness more but i wanna learn pcm tuning anyways, just need to do it sooner than expected now.

 

Grab a copy of "PCM Hammer" for use with that VX Nano and go do it!! Then save off a file copy of the tune on a thumb drive for future use as an insurance policy.

Rick

 

4L80 TCC is activated by GROUND on Pin 'S' might be a brown wire.
Pull out pin S, and TCC should NOT lock.
Figure out if harness is short to ground ( pinched wire) either internal to trans case, or outside.
I have seeen pictures of serious wire harnes rash, with skinned wires near Trans connector.