Hey Guys,

This is my first post here, but I've been working on this issue for a few months now and I cant find the information i need.

Basically I have a 96 GMC Jimmy S15 with the 4.3 and 4l60e 170k, one day i started the car the SES light was for one code only "P1864 TCC solenoid electrical fault" basically the torque converter is at full lock so it bangs into 2nd gear but all other functions are normal except no overdrive at all. I did some testing and I was though it was a solenoid, so I replaced the TCC solenoid and the entire internal wiring harness inside the 4l60e, since it was so cheap with, but no change what so ever, same code, same symptoms. No new codes. so I dropped the pan and flushed the fluid 3 times for nothing lol.

I did a little more testing and turns out the wiring diagram i had was wrong and both TCC wires on the trans harness (both pink wires) have no power at all, they are supposed to be 12v switched power.

I've heard the ignition switch can cause this so i tested the pink ignition wire in the column and thats fine, so somewhere in between the ignition switch and the trans theres an issue.

My question is does anyone have any wiring diagrams for the body side of the transmission? are there any relays behind the glove box that could cause this? if anyone has had any experience with the please help!!!

Thanks for any input

- Preston