Does the PCM control the 4l80e? I keep hearing how I'll need a TCM to control it, but I was under the thought process that the TCM was only necessary if I was using a carb setup.

Is the TCM an external or internal device if it is needed?

My mustang has the painless 4l60e harness but has always had either a t56 or th350 in it, but all the plugs are there. I just wanna put this thing in as cleanly as possible

 

Depends on the year of the PCM. Newer PCMs don't control the transmission, and it has a seperate TCM.

 

its a 99 ls1 pcm

 

Then your PCM controls the trans.

 

ok whew, i know i gotta repin it and all, i was just hoping i didnt have to buy another module

 

you'll have to get a segment swap