I did some of the tests in the transmission diagonostic book, and assuming my voltmeter was right and i was probing the right locations, everything points to a bad TCM. Is it possible that the solenoid assembly has gone bad as well? I have troulbe believing ALL 3 sensors are bad, especially with the new governor solenoid. How much is a TCM and the solenoid assembly?
The diagnostic book indicated that if codes 22 AND 23 are present, that it's wiring somewhere. Nothing has been done to disturb the wiring that i know of, but who knows with these things!
I got my TCM from the dealer this morning, and plugged it in. No errors right away (which means I'm at least that far ahead of it...). Drove it around the neighborhood for a few minutes and had no problems. Got back to the house and checked for codes, and none were there. Went ahead and mounted the TCM where it should be and then went to work. Shifts are much smoother than I ever remember, and I don't have the 3-4 delay when it's cold either.
Just for reference, the number on the module that came out of the Jeep was 5602 7564. The number in the parts sheet is 5602 7316, which seems to also be what salvage yards have. If you go to a salvage yard looking for this, you may want to tell them the 2 numbers and that they are the same. In fact, it doesn't even appear as if they make the module with the 7316 number. If you order from a dealer, you'll get part number R602 7564, which means it's a remanufactured unit. They only have the remanufactured modules now, but it seems to have (hopefully, knock on wood, say a few hail mary's and amens) fixed most, if not all of the tranny problems I was having.
Drove it a bit this afternoon, and I don't know if it's the computer(s) relearning all the settings and data, but it drove like crap. The tranny seemed to be good, but the engine was awful at idle. I needed to run to the store, and came out about 5 or 6 minutes later, and it idled like it was misfiring. Hit the gas and it was ok, but when it got back to idle, it was almost a surging feeling. When it wasn't doing that, it idled way low (just above the first mark on the tach). I switched the A/C off, and that helped. Drove it like that for a bit, and it seemed to idle fine after that.
Any ideas on the idle? The IAC is only about a year old. Could probably stand to clean it, but any other thoughts?
Hope this info helps someone with the same problems (or similar) to what I had and they don't have to deal with all the trouble I did to track the module down!
Alright, I know this is an old *** post but I need to thank you and the great car god that I found this post this morning. My 42re went into limp-home mode Friday morning with a code 21 so I bought an installed the governor pressure sensor and solenoid. The problem persisted so I thought I would need (junkyard) transmission. I pulled the codes again this morning and got 21, 22, and 23. I found this post and thought that a $50 junkyard TCM was a decent wager vs. a $600 junkyard tranny. I found the ONLY one in Austin, threw it in, and BAM, problem solved. THANK YOU!!! It solved my limp-home mode and a bunch of other minor transmission problems that had been popping up at random for the last five or six months.
I've been working on a customers 93 jeep grand Cherokee with the 4.0l and the 42RE trans. When i got it it was starting and staying in 3rd gear, no overdrive. You could put it into 2nd manually but not first unless you went strait from neutral to 1st.
Got Codes 21, 22, and 23. I changed the tps because it was easy and free but made no difference (it was a shot in the dark, I read sometimes this could do the fix.). Found this post and decided to buy a used tcm, Model # 56027218 on tcm. I got the only one in the sacramento area for 100 bucks, Installed it and the new one fixed the problem. Shifts like normal and has overdrive back. Hope this helps someone else, working on these things sucks.
Also the tcm is located on the inside of the firewall left of the column, the nuts are two 13mm on the engine side of the firewall, no need to remove any dash plastic. see ya.