I changed out the speed sensors because I had a P0715 a little over a month ago. As far as I know, everything on the car is stock/original from what I can see, or so I will assume, since I'm not the original owner. I'm from the school of thought that if the input sensor went bad, then it's not long until the output sensor goes too, so for an extra $30.00, I decided to replace both. It cleared the P0715 and the GC drove normally until this P0732 a few days ago.
Sorry, that's my mis-understanding of limp mode.. I thought it was the electronic tranny limiting access to certain gears to protect the engine. My GC shifts back to 1st when I come to a stop. I'm not slipping in 1st. I only used my scan tool, and I got matching pressures (124.97 if I remember correctly?). I did not attach an external gauge. For the record, the autostick doesn't work either.
The issue is that after the "jolt" into 2nd, I don't feel it shift past 2nd. The revs just climb proportional to my speed no shift is observed or felt. For example, at 70mph, I'm running at 3,500 RPM's, instead of the RPM needle hovering just above 2,000 at 70mph normally. For that reason, I haven't been driving the GC above 50-55mph (about 2,300-2,500 RPM under current conditions). I have no other vehicle so I have no choice but to drive it, even though I probably shouldn't. Other than the above mentioned issues - jolt into 2nd and the apparent lack of higher gears - the GC drives absolutely normal.
If I can't figure this out soon, I'll have to find the time to bring it to a tranny shop...
Like I said, I definitely have to get under the vehicle and pull the pan. Tomorrow I have a day off so I hope to get under my GC. I haven't ordered anything yet. Just want to get some more input, and finish the diagnostics as per the FSM. I'm up to step 11 of 15, which says:
"11. UD ACCUMULATOR PISTON
Check the UD bleed orifice, accumulator piston, and accumulator piston seal in the main valve body.
Were there any problems found?
Yes >> Repair as necessary. Refer to the Service Information for proper repair procedures.
No >> Replace the Transmission Solenoid/TRS Assembly per the Service Information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1."
My thought was possibly the solenoid (I would have also suspected the speed sensors had I not replaced them) before I began diagnosing the issue. The FSM states to replace the solenoid if no issues found, which seems to reinforce my thoughts. I'm not jumping to coinclusions yet, as I still have steps 11-15 to run thru, plus Frango's advice (I actually work very methodically). I will post as I progress. Thanks for your help Frango!