I had an issue a few months ago with my 3-2 downshift solenoid, which caused the car to start off in third gear.

I pulled and replaced all the solenoids and replaced the PCM, and everything seemed ok on multiple test drives. Drove the car two days ago, and had the same problem I experienced before. The difference, with the first PCM I experienced the problem IMMEDIATELY. With the stock LS1 PCM I'm not noticing the problem until much later.

I drove about 15 miles around town, and during the last 3 miles of the drive returning home it started acting up, and once again defaulted to third gear for all driving situations.

I can't find any breaks in the wiring...and would much rather not drop the pan a second time. Anyone have any other ideas as to what's going on?

The PCM I'm using was a spare unit, so I can't GUARANTEE that it's trouble free. So that's a potential problem. I'd rather not take the car in to have the transmission inspected, because I know a shop will simply say "rebuild it" and $1000 later I may or may not have the problem solved. Hopefully there's a 4L60E expert here who can help me out.

 

Is the transmission harness ok and what year 4l60e because they make two different 3-2 down shift Solenoid

 

If the transmission was working ok before the problem, it is an electronic problem.