nlawson6.0

iTrader: (26)

okay i just swapped in a fresh 80 and i went over all my wiring and it acting weird. on the stands it go in to forward and reverse but when the tires get spinning under throttle, when i apply the brakes it kills the motor.

its throwing 2 codes
PO740 - TCC Circuit Malfunction
PO785 - Shift/Timing Solenoid Malfunction

if anyone has so input to what may be the problem please chime in..

also..
Nelson did the tuning part..


thanks,
-Nate

thunder550

iTrader: (70)

Did you swap the brown and white wires in the round harness?

nlawson6.0

iTrader: (26)

i did it at the pcm

i pulled the brown wire out and put the white wire in its place

and added the vss

thunder550

iTrader: (70)

Maybe something in the internal harness is unplugged or broken? Did you have another 4L80E in there before that was working ok or did you just do the conversion?

nlawson6.0

iTrader: (26)

i had a 60e.

-Nate

thunder550

iTrader: (70)

You're sure that he did the 80E trans segment swap in the tune?

nlawson6.0

iTrader: (26)

i told him that i swaped in a 6.0 and a 80e. called a week later and was told its taking alittle longer than expected because the 80e swap. so.. i would hope so.

thanks thunder

-Nate

thunder550

iTrader: (70)

If the tune is good then I'd start checking wires. Make sure you got the pins seated fully in the PCM connector. Double check that you swapped the correct ones. Check the round plug on the trans, and pull the pan and check the internal wire harness and make sure that it's ok.

My hunch is that the tune is not correct or that something is not right in the wires you swapped. I can't remember 100% for sure but I think those codes you have are the ones that get thrown because of the wiring difference between the 60E and 80E.

Check out this thread.
https://www.performancetrucks.net/fo...ht=p0740+p0785

nlawson6.0

iTrader: (26)

yes those are the codes im throwing... so it sounds like i need a tune fixed..

stock48

iTrader: (16)

Sorry to hear about your troubles. I can vouge that Nelson can tune the trans. He did my base tune, and the trans programing is the only thing I havent touched other than lock up, and shift points. Two years of running 10's on a shift kitted stock 80E and still works flawless, and not a spec of anything in the pan.

Hows the cam working out?