P0988 Transmission Issue - Need Help
I have a 2005 WK Grand Cherokee with Hemi and 4WD. Recently I've been getting the P0988 DTC Code and my transmission goes into limp mode after about 20 miles of driving. When I clear the code, the transmission shifts normally, until the code appears, then eventually limp mode in 3rd gear.
P0988-4C PRESSURE SWITCH RATIONALITY only.
No other codes show up.
Things I've done so far.....
Took my Jeep to the Dealer in Aurora Ohio. They held my jeep for two days and said they need more time troubleshooting. When they started to give me the BS that something was wrong with my MSDS system in the Hemi I asked for my jeep back. Extremely poor service.
I have a factory manual on CD and an OTC Nemisys scan tool. Reviewing the manual, and since no other codes were present, I replaced the solenoid valve pack in the transmission. The 4C pressure switch is in the solenoid pack. Still have code.
I disconnected the wiring harness at the PCM and verified the 4C wire is shorted to ground at the PCM from the transmission. This is why the code is set. I disconnected the harness at the transmission, and the short is removed. Thus the wiring harness is ok.
Now I am stumped. What could cause the 4C line to short to ground and stay shorted? I checked the 4C pin on the removed solenoid pack, and its open as it should be. Something on the valve body is causing the 4C line to short to ground. I am determined to drop the transmission pan one more time before I take it to a transmission shop. Any ideas?