4t60e question

On the 4T60E (1996) transmission, what 'should' happen if you disconnect the harness on the front of the transmission (the round plug)? The transmission has been upshifting harshly lately, and from what I thought I had read,I thought that disconnecting the harness would let the transmission go into a 1-2-3 pattern, with maximum pressure, but should operate normally otherwise. I disconnected it to see if it was some sort of electrical problem causing the car to act this way since I've had various electrical problems with it over the years.

Instead of doing what I thought it was supposed to do, the car dropped from 1st to 3rd at about 5 MPH, and stayed there unless the car came to a complete stop, to the point that I went about 200 feet and stopped the car to reconnect the harness before it tore the bottom out of the engine. Did I read the wrong thing about disconnecting the harness? I certainly won't try that again (and I know I'm lucky that
I didn't destroy something), but for informational purposes, what would have caused this to happen? I've already got the car scheduled for the shop this week, but they have looked at it already twice and can't tell me what is wrong with it. Perhaps someone knows a good transmission shop in the Raleigh, NC area?

Thanks. I'll have it scanned this weekend. Knowing that I should be looking for something from the shift solenoids helps out a bunch. I don't know much (obviously) about transmissions, but I'm the person who will have to fix this one and I'm totally out of my element.
Thanks very much for the information.

All you did here was force the pcm to revert to limp mode when it saw no continuity to the various controls. have the trans scanned for solenoid operation and codes, keep in mind a code probably set by disconnecting the main harness, an ordinary scanner will do do what you need to get into the trans diagnostics.

i am from smithfield nc. i think your problem is govener is sticking 2-1 down shift should be 10-8 miles hour 5 is not correct.sticking govenor i have 91 chev luminia 91 delta 88 both had this problem cheap and dirty fix trans-x 2 cans do not drain off surplus you need all the pressure to flush out valve controls and govenor add one thrid can every two days hot trany also trans sealer add all at once worked for me save 1800 to2200 dollars.