indeed to convert a 4L80E into full manual.

[hippykewl]

I have a '94 GMC with a 5.7Motor it previously had a 4L60 mated to it but I have just put the 4L80E in it. I now need to rewire the external wiring harness plug to convert it into full manual operation can you give me any assistance in how to so this?

 

[Jaryd]

I think there is a write up on how to do that on this forum somewhere. I can’t help because I’m not a trans guy but you can try searching on here for it.

 

[MrMarty51]

HiYuh Hippy, Welcome to the truck stop.
I always thought the lever on the column was for manual operation of the transmission.

 

[FellowTraveler]

I had a few years ago looked into the TransGo full manual kit for the 4L80/85 and found it does not work with a diesel but its a go with a gasser.

 

[WarWagon]

Do it without wires...

 

[ak diesel driver]

IIRC member deejay did a full manual on his truck

 

[THEFERMANATOR]

The easiest way is to use the jakes kit. Otherwise you have to get a wiring diagram, and find the pressure switch outputs, and wire the apropriate pressure switch output to operate the correct solenoid sewuence for each gear. The downside to this setup is line pressure control will be locked at max pressure unless you install somethi,g like transgo's vacuum pressure control modulator to vary line pressure.