This is great @NMH3 thanks so much for sending that over. I did drive it for about 30 minutes this morning and scanned for the temperature readings. It was only 73 degrees here this morning but everything seemed to be reading okay. Coolant temp is a bit high here but I was parked with the engine running for about 5 minutes and that's generally the temp I see when I've been checking things before. Pretty much steady around 204 degrees when I'm driving. I'm planning on reusing the filter since I just replaced it on August 20 but I did grab a new gasket.


trans temp reading at 185 degrees after 30 minutes of driving.


not sure why the 3-2 Downshift solenoid is labeled "off" here or if that's expected.


Thought it might be valid to show the slip counter at 0.

 

Someone please save me and tell me how to remove the transmission pressure control solenoid. I can't get it to back out more than 1/4" for some reason. I unbolted the retainer clip and need to get that solenoid out of the way in order to remove the wiring harness. It seems like the black plate behind it is barely in the way. Do I need to remove the spacer plate, too @Doc Olds ?? Instructions say I don't need to but this thing just won't come out.


trans pressure solenoid

 

You probably already saw this.

To remove the pressure control solenoid (EPC solenoid) on a 4L60E, you must first drain the transmission fluid, then remove the transmission oil pan and filter, and detach the valve body. The EPC solenoid is located on the valve body, and after disconnecting its wiring, you will need to remove the 8mm bolts holding it in place, along with the special fork holding the solenoid in position, before gently twisting it out.

Tools and Supplies Transmission fluid, Socket set (including 8mm and 10mm sockets), Screwdrivers, Pan and funnel for fluid collection, and New solenoid kit.

Step-by-Step Instructions

1. Drain the Transmission Fluid:
   Place a drain pan under the transmission and drain the fluid, as you will need to remove the pan to access the solenoids.
2. Remove the Transmission Pan and Filter:
   Once the fluid is drained, carefully remove the transmission oil pan and its internal filter.
3. Detach the Valve Body:
   The solenoids are mounted on the valve body. You will need to disconnect the wiring harness that goes to the valve body and then remove the 10mm bolts securing the valve body to the transmission case.
4. Remove the EPC Solenoid:
   • Locate the pressure control solenoid (EPC) on the valve body.
   • Disconnect its wiring by pressing on the small latch.
   • Remove the 8mm bolts that secure the EPC solenoid and the special fork that holds it in place.
   • Gently twist the solenoid to remove it from its position.
5. Inspect and Reinstall:
   Carefully inspect the valve body and the pressure manifold for O-rings, ensuring they are clean and undamaged. If replacing the solenoid, align the tab on the new solenoid's fork with the tab on the valve body before securing it with the bolts.
6. Reassemble:
   Reverse the removal process by remounting the valve body, replacing the filter, installing the pan gasket and pan, and finally refilling the transmission with the correct type and amount of fluid.

 

In other words, twist & wiggle while pulling it out.

 

Thanks Doc. I went back and look at the instructions closely and I did end up having to lower the valve body. Did not need to remove entirely but all the bolts needed to be loosened.

Here's my issue now. I got everything swapped out, bolted back up, and added some fluid. Only had about 2.75 quarts left in my bottle and I drained roughly 3.25 quarts last night but I thought it'd be okay for a quick test drive. The instructions recommended resetting the transmission adaptive pressure values so I did that using my scan tool. "Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, The ECM, PCM or TCM will need to relearn TAP values. Transmission performance may be affected as new TAP values are learned."

Started it back up and tried to shift into gear and it won't budge. Also getting traction control and service stab system warning lights. Not sure where I went wrong or need to look now.

 

Here are my codes. Any help or idea would be appreciated. Haven’t tried to manually change gears with the button under the center trim piece yet.

 

Fill the fluid then see what you have.

 

it looks like you have some wiring grounding out because even the transfercase actuator is complaining about being grounded out not only the transmission.
you need to look for chafed wires. look around the back of the intake where it goes into the tranny tunnel. also look wherever there it a tiedown or ziptie

 

Added about 1.5 more quarts, started it up, and all codes disappeared and was able to shift out of park. Thanks so much to this whole community for dealing with my insanity and responding to random tangents and posts. I'll spend some time later tonight writing up all of the stuff I dealt with last night and this morning to close out this thread but it seems as if I just needed more fluid. Only took it out for about 5 minutes and wasn't able to get up to highway speeds to check and see if 4th gear engages now but I will this weekend for sure.

I really did try my best to capture/measure all the fluid I drained out and add that same amount back in. Obviously didn't account for everything dripping out for a few hours as well as what I lost when I lowered the valve body. It was after midnight last night and I had already been on my back for 6 hours so I gave myself a pass.

@bronxteck I did spend about 5-10 minutes looking all around for any wiring issues but didn't see anything that stuck out as a potential problem. I think I might have secured the main 20-pin connector to the harness a bit better than what I originally had, but I was reaching around the driveshaft and over the transmission protector plate so it's hard to say for sure. It's a pavement princess through and through so the underbody and wire tubing is all still in really good shape. Could you be more specific on the location you were talking about, though? Do you mean the area down below the fire wall under the hood? Hard to get a good look from above and I didn't take the skid plates off for this job.

Thanks again to you and @Doc Olds and everyone else. This forum is a lifesaver for guys like me who love their H3 and would do whatever it takes to keep it going! I had never even changed my own oil before 2019 and hummerforums is by far the biggest reason why I feel somewhat comfortable with handling all of these complex issues.

 

@KU1525 and we appreciate you sharing of your repair and upgrade adventures. I know I have learned from them.