BTW, thanks for posting those links about vacuum testing. My transmission is working fine, but I'm trying to learn as much as I can, just in case of future problems.
Yeah man, I've seen so many of these threads hit dead ends with no resolution-- If I'm going to ask for help, hopefully I can leave a thread that can help someone else in the future, and even better if it helps you guys that are helping me along!
Just to clarify, you're saying your test verify my CPP/PNP results are as they should be? Out of curiosity, how'd you manage this without FORScan? I guess I don't even understand what this PID is looking at. What is in Neutral or Drive?
Further, you're saying CPP/NDS is likely similar to that Trans Range PID that is incorrectly labeled and/or not functional?
So last night I pulled the VB and found some potentially interesting stuff. It looks like it may have been dropped? The rear wall on the protruding section that extends next to the servo cover looks deformed with two hairline cracks. Neither seems to be all the way through, the adjacent valleys seem to just be retaining clips for the EPC booster valve and pressure reg valve. That said, that Sonnax vacuum testing sheet linked above does call out the EPC booster as a possible cause for a no reverse condition. The only other thing I noticed was the pictured possible gasket failures. Since all pieces were present, I'm unsure if the breakage was present, or if it was caused by disturbing the gasket in disassembly. Two of the spots are not pressurized, but mounting through holes. It is the bonded plate/gasket assembly. The one potential blowout is not adjacent to a passage called out by Sonnax for a no reverse condition, but the way everything is interconnected, it's hard to rule it out with my limited knowledge.
Lastly, as I was testing yesterday, I noticed a distinct hissing noise from under the cab when reverse was selected, and only when reverse was selected. Pressures are highest in reverse. I was alone and didn't feel safe crawling under while the truck was in gear, but it's possible this sound was coming from the pressure gauge that's hooked up to the EPC test port-- but I'm open to theories.
Onto the pics:
VB Damage:
A pic of another 5R55E VB that seems to show that the VB wasn't cast this way:
Gasket: