S1CERVANTES

Okay so this is my first official post. Pretty excited to start posting and hopefully get some replies. This is my first Jeep. It is a 93 Grand Cherokee 4.0 l straight 6 . 250000 miles with a 42re automatic transmission and 231 J transfer case with 272 ratio. I will try and make it as detailed as possible so we can hopefully narrow down the issue. I purchased a 93 ZJ for 300 bucks. Well for starters it's had one owner who was not mechanically inclined. The engine runs like new but unfortunately it appears the oil pressure switch was leaking for quite some time. All of that oil eventually ran all the way down the passenger side of the vehicle along the engine and transmission wiring harness. So you can imagine there was years of oil and dirt piled on everything. When I finally got a battery installed in a track bar installed I took it for a spin and it was in limp mode and overdrive light wood Flickr when shifting between Park and reverse and from Drive into manual 2nd. They told me it ran fine but I can bet they had no clue it was in limp mode and assumed it ran fine. After inspecting the transmission harness and connectors I noticed the 8 pin connector to the overdrive had a huge glob of silicone masking the exposed wires at the plug. All wires made a connection but we're completely exposed just behind the connector. I immediately swapped it out with a new 8 pin connector once everything was spliced and heat shrink I plugged it back in and turned it back on now my overdrive light was on constantly and would not turn off even by pressing the overdrive button. I took it for a spin and still in limp mode. My next maintenance was switching out the overdrive solenoids / Governor pressure solenoid and sensor. Once that job was completed close the tranny backup sealed the pan filled her up with fresh fluid and filter. Ran her through all gears and topped the tranny off with ATF. Now my overdrive light turned off but was no longer functioning. Still in limp mode and overdrive light would Flickr randomly. This to me was starting to look like a short. I had a spare TCM and swapped it out. Still in limp mode but now my overdrive light turned on and off as it should by pressing the button. Had my wife sit in the car with engine on and OD light on as I wiggled the engine harness at different points. The light seemed to flicker most when wiggling the harness closer to the PCM. I could not find any exposed wires making contact to anything. The light flickered in that general area where the transmission harness splits to the PCM and the other wires split 2 the fuel rail, throttle position sensor, IAC Etc. Just above the oil filter where the leak was. Just for kicks and Giggles I disconnected the PCM harness and gave it a full Twist to cause tension within the harness and plugged it back into the PCM. Bingo! My light no longer flickered and was turning on and off by pressing the OD button. I took it for a spin and it started in limp mode and within 5 seconds or so of accelerating it downshifted and began to shift properly! I took it for a spin around the block a good four times and it would shift but at random points would want to almost go back into limp mode. Tranny went back into limp mode . Brought it back home checked the fluids and I had to add another 2 quarts because the tranny had sucked up more fluid. Took it back out and it begins shifting properly again only this time as I was maintaining a consistent speed it would jump in and out of limp mode. This is where I started scratching my head. I would turn the overdrive off and the light would come on as it should. The minute I accelerated the light would flicker off and overdrive would now be on I'm assuming because it was shifting past third. Would it possibly be a bad overdrive button? Even though it turns on and off when I press it? Or could it be a short within that circuit? Obviously pressing on the accelerator causes this short within the overdrive light any help would be much appreciated thank you

S1CERVANTES

Oh yes one more thing. My oil pressure gauge had been very erratic period always at 40 but the minute I touch the accelerator it would Peg at 80 then eventually come back down to 40. I changed out the oil pressure sensor because it was leaking mind you it was already in you oil pressure switch. Put in the new one and the glitching went away but now my oil pressure is constantly at 60 and when I accelerate it bumps up to 70 75. Is this normal?

kjc

Sorry, i'm unfamiliar with "limp mode", but I have the same model you describe w/o the OD button. You might check your brake light switch.. If it's sticking or mis-adjusted, it can affect OD and torque converter lockup as well. What exactly is "limp mode"?

S1CERVANTES

its when you have no overdrive and your tranny is stuck in 3rd. Wow I had no clue the brake light switch can have that affect on OD and the such. Thank you.