I am not sure about you, but I am not a big fan of getting into a job that someone else has already been working on and failed to resolve the issue. I was not aware of this when I got assigned to diagnose a 2009 Jeep Wrangler with a 42RLE transmission. I started my evaluation with the customer concern of "cannot get out of park at times". I walked out to the vehicle with scanner in hand, opened the door and what do I see? The whole center console is out and in the back seat...ugh. The vehicle came to us from a used car dealership that has their own "mechanic". What was I going to get myself into? I started to look around and try to see what had been done, and I saw a new shift cable, a new shift interlock solenoid, and a new brake lamp switch; it appeared that throwing a bunch of parts at it failed to "fix" this one.
After checking fluids and scanning vehicle for codes I decided to go for a road test, the Jeep came right out of Park so I tried it a few more times and it seemed to work fine, each time it came out of Park with no extra effort. I continued on with the road test to make sure that there were no other issues with the operation of the transmission, it shifted well, no slippage, and TCC operation is functional, everything seemed to be operating just like it should.
When I pulled back into the parking lot I put into park again and this time it locked into park, I could not budge the shifter. With the console already removed I could see the shift cable mounting bracket flexing when I tried to force it out of Park. It seemed that I finally experienced the customers concern! The scanner was still connected, so I looked at the brake switch and the interlock PIDs and they were both being commanded. Since the console was off I could physically see the interlock working, but it still would NOT come out of Park. I then blocked the wheels and got under the Jeep and disconnected the shift cable from the shift lever on the unit and I could not budge the shift lever, but from inside the vehicle the shifter and cable now moved freely. This confirmed that the problem was inside the unit. Perhaps if the prior tech would have taken a different diagnostic approach, they probably could have saved some money.
At this point the Jeep was sitting in the parking lot stuck in Park and I needed to get it into the shop, so before I pulled the driveshaft to accomplish this, I had a couple guys come out and "rock" the Jeep to see if it would come out of Park. It made a loud "pop" noise and then came out of park, so we pushed it into a bay and finished up the evaluation. I turned in the paperwork with the recommendation to pull the pan and valve body for inspection. The technician pulled the pan and it was clean, and vehicle only had 50k miles on it so I was pretty confident that we could fix this without having to replace the unit. I gave the tech some brief instructions and reminded him to put the shift shaft into manual low position before trying to remove the VB.
With the valve body removed and on the bench, I did not see anything blatantly wrong with the park mechanism, but upon closer inspection I noticed that the rollers on the Park rod did not seem to "roll" very easily. We had some parts sent up from our remanufacturing plant. I installed a new Park rod and the rollers moved freely so I knew something was wrong there, but was it enough to cause our issue? When I was trying to spin each roller around on the original one, I saw it, there was a flat spot on one roller and on the other one there was one section that was pitted: (Figures 1 & 2)
Figures 1 & 2
I am not sure if it was just one roller or if both of them had to be in a certain position for it to bind up the park linkage like it did, but that would explain why the problem was not always apparent. I took a couple of pictures and sent them to our tech director for that unit mode; and asked if this was something we had seen before, and he stated it was not. There are a couple other things inherent with that unit involving Park issues, but the damaged park rod rollers was not one of them.
Using a remote camera to inspect the park pawl a little more closely, we really saw no other damage. Park is not something that you want to take any chances with. This unit was not one of ours; if it had been, we would have replaced the entire unit because we do not allow repairs for Park concerns in the field. Since this was the customer's unit, we replaced the park rod put everything back together. After the repairs were completed, I took the Jeep out for a good test drive. I stopped on a hill, engaged and disengaged Park several times in both directions, and it performed flawlessly by both holding park and coming out of park. It's possible that this transmission had an issue right from the factory and just progressively got worse; nonetheless the new part got it right again.
The new park rod is still available from FCA Part# 4800283AA. Retail cost $26.85.