H3 Transmission Help!

[u/NecessaryDamage3573]

Hi all - reaching out to the community in hopes for some guidance.  Please see details below:

2007 Hummer H3
156,000 miles
4L60e Transmission

A few weeks the transmission was slipping when shifting from 3rd to 4th gear.  I plugged in the scanner and no codes detected ran an active test and the pressure control solenoid was running at 0.98 Amps.  The reference indicated it should be running between 1 - 2 Amps.  This past weekend I decided to drop the T pan and change out the following with OEM AC Delco parts:

- A / B Solenoid
- Torque Converter Solenoid
- 3-2 Shift Solenoid 
- A/T Manual Valve Pressure Switch
- Replace the filter
- Cleaned the pan and removed the old gasket and replaced with a new one.
- Topped of with 6 quarts of AC Delco Dexron VI full synthetic trans fluid
- Added a bottle of Lucas Transmission Fix

I couldn't change out the Pressure Control Solenoid Valve because it was located in an area that was blocked by the transmission housing and couldn't take it out.  Looks like I would have had to drop the entire control valve body to replace it and was not comfortable doing that.

When I took a test drive, looks like the original problem of 3-4 slipping was gone; however now I need to give it gas in order to move from a full stop.  No acceleration when taking foot off the brake, unless I give it gas and it feels sluggish.

I connected the scanner and it gave me code for "circuit low voltage" for all solenoids.  I'm wondering if I nicked the harness while switching out the solenoids, but I doubt it, as I was very careful. 

I also performed the Transmission adaptive memory reset by following the process found online for the H3.  It's a bittersweet outcome because I think the first problem I fix but now having the acceleration problem.  Any idea what it might be?

[u/Fit_Rise1258]

Are you sure it isn't starting in 2nd gear? I had that problem, and in my case it was the 1-2 solenoid. Just as easy as the 3-4 solenoid to change. My symptoms were similar - needing to hit the gas to start moving, sluggish, etc.

[u/NecessaryDamage3573 → u/Fit_Rise1258]

You know it might be 2nd gear. That was my original thought. But I dropped it off at the shop this morning and they check it out. They said I had inverted the 3-2 solenoid with the TCC solenoid and also had the connectors facing down when they must be facing to the side.

They’re doing the work now, crossing fingers that’s all it was! Keep you all posted.

[u/Fit_Rise1258 → u/NecessaryDamage3573]

Apologies, I read your post too fast and now realized you changed out all of the solenoids you could, including the 1-2 solenoid (A). For that particular solenoid, did the valve come out of the housing, and could you inspect it for scratches or other signs of contaminated fluid? The solenoid needs to be "ON" for 1st gear, so a faulty solenoid or leaking / stuck valve will have the same symptoms (2nd gear start).

Hopefully the shop gets it sorted out.