Help with 42RE: NO LOW GEAR and OVERDRIVE (MOVES IN 2ND OR 3RD GEAR ONLY) - JeepForum.com
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post #1 of 22 Old 05-10-2021, 05:33 AM Thread Starter
Gulibert
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Help with 42RE: NO LOW GEAR and OVERDRIVE (MOVES IN 2ND OR 3RD GEAR ONLY)

Hello,

I have the NO LOW GEAR and NO OVERDRIVE in my 1995 Jeep Grand Cherokee ZJ with 42RE transmission. The problem started this spring and was sporadic. I ordered the Solenoid Service & Upgrade Kit 42RE 44RE A-500 1993-97 Heavy-Duty (21496) and replaced them. While I removed the valve body I've seen that the case had a 1996 year stamp on it, and hence had already the upgrade installed. The assembly went fine and the test drive same day about 10 miles was perfect. The very next day, same problem as before the change was there.

The service manual says:

1. Governor Valve Sticking: Remove governor, clean, inspect and
repair as required.
2. Governor Circuit (RE Only) Electrical Fault: Test with DRB and repair as required.
3. Valve Body Malfunction: Remove, clean and inspect. Look for
sticking 1-2 shift valve, 2-3 shift valve, governor plug or broken springs.
4. Front Servo Piston Cocked in Bore: Inspect servo and repair as required.
5. Front Band Linkage Malfunction: Inspect linkage and look for bind in
linkage.

Unfortunately I did not find any step-by-step instructions (or better video) for 1, 3, 4 and 5 and also for 2 I do not have anyone with DRB at the moment. I am OK with removing the valve body again since after the 2nd oil refill I will have most of the oil changed but this time I like to be better prepaired.

What would you suggest to check as the next possible cause since I know that the parts that I changed were good?

What of the 5 causes would be something that cannot be repaired without the help of a professional?

Any advice is greatly appretiated.

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post #2 of 22 Old 05-10-2021, 06:39 AM
yjsaabman
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I had this problem and found I had blown a fuse for the transmission control module while doing something else. Might want to go through and double check all your power and ground connections to the transmission and all the pins in the electrical connectors.

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post #3 of 22 Old 05-10-2021, 07:17 AM
zjosh93
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For the 93-95 with a separate transmission control module (TCM), if the pressure sensor and solenoid didn't fix the problem, the next place I would look is the TCM. They do go bad not infrequently. A bad TCM has the same symptoms as a bad sensor and solenoid.
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post #4 of 22 Old 05-10-2021, 10:06 AM Thread Starter
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@yjsaabman
Suppose the fuse was blown then the symptoms would be always there and it wouldn't be possible that there are days where it works, right? Was the fuse you changed in the main fuse panel? I will check them anyway.

@zjosh93
I will then have a look if I can get replacement. Does it have to be from the years 93-95 or is it possible to use a later one, like 96/97? I heard of a problem with capacitors. Will also check the module because we had a raise in temperature last days and if it is the TCM maybe a bad connection is the cause.

I also have this:

When switching from N straight to 1 I get the first gear. Then I can switch to 2 and D but when making a small pause in D when I am going from N to 1 it will go straight in 2 and never in first. So I have to do it in one pull. No way I can get back to first once I was in second (or third).
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post #5 of 22 Old 05-10-2021, 10:35 AM
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Quote:
Originally Posted by Gulibert View Post
I will then have a look if I can get replacement. Does it have to be from the years 93-95 or is it possible to use a later one, like 96/97? I heard of a problem with capacitors. Will also check the module because we had a raise in temperature last days and if it is the TCM maybe a bad connection is the cause.

I also have this:

When switching from N straight to 1 I get the first gear. Then I can switch to 2 and D but when making a small pause in D when I am going from N to 1 it will go straight in 2 and never in first. So I have to do it in one pull. No way I can get back to first once I was in second (or third).
Yep, that's how the trans acts in limp home mode.

The 96-97 integrated the trans control into the PCM. They don't have a separate TCM. AFAIK any 93-95 TCM will work. I've had a 95 or 94 TCM in my 93 and it shifted exactly the same.

The TCM failure is usually one of the relays on the board but it probably doesn't hurt to replace the caps too. I fixed mine. The info is here (https://www.jeepforum.com/forum/f13/...cment-1604113/) but photobucket ate my pics.
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post #6 of 22 Old 05-10-2021, 12:24 PM Thread Starter
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@zjosh93
Many thanks! Just now I am desperate finding the TCM. It says " It's mounted on the passenger compartment side of the firewall, behind the steering column."
Inside the car or inside the engine compartment? Perhaps my 1995 has the TCM already installed in the PCM which is right/passenger site engine compartment.
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post #7 of 22 Old 05-10-2021, 01:04 PM
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On the inside of the firewall, above and slightly to the left (outside) of the brake pedal. It has studs that go through the firewall. You can see them on the engine side to the right (outside) of the brake booster. Not hard to get out, just two nuts and one wire connector. Have to wiggle it through the under dash wiring but not bad.
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post #8 of 22 Old 05-10-2021, 01:27 PM Thread Starter
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Finally found it - thanks!!! Took it apart, looks very clean. Changed the 470u/35V capacitor, took out the relais, checked with 25V to assure it was switching, put it back and even soldered all connectors contacts. Put all back and the fault still persists.
You also mentioned a fuse. Is this sitting near the TCM? Didn't find it so far and any other fuses checked were OK. Maybe the TCM is completely dead and wakes up from time to time... Stuck where I was before...
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post #9 of 22 Old 05-10-2021, 02:03 PM Thread Starter
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My hope is rising... I disconnected the TCM to see if there is any change, and - there is none :-) So it looks like a dead PCM to me. Just want to make sure it is not a broken cable / contact near the fuse which some have mentioned. Care to tell me, where to look for the fuse?
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post #10 of 22 Old 05-10-2021, 02:22 PM
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yjsaabman was talking about the fuse. I mentioned the relay in the TCM, did you check it for burned pins? I went ahead and reloaded the pics to my other post. Should be good now.
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9.jpg  
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post #11 of 22 Old 05-10-2021, 02:26 PM
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Yes, when the fuse was blown it was a constant problem. It was in the main fuse block under the hood and was also labeled for the airbag system. It was 20A fuse, IIRC, but I don't remember what number.

I keep trying to remember if I kept the TCM out of my 94 when I did the 5 speed manual swap. I'll have to look for it tonight, if I remember.

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post #12 of 22 Old 05-10-2021, 02:28 PM Thread Starter
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Great answer & thanks for the pics! I guess this is the only post you opened that explains how to fix the problem :-)
Yes I did as you said but in my case the contacts of the relais were clean and it was clicking when voltage applied. As I wrote earlier, when I disconnect the TCM there is no change in switching behavior. I understand that the 42RE will drive even with no TCM installed and that it will have 1st and Overdrive missing. Small chance that there is a problem in wiring and/or the fuse. Otherwise it is the TCM but I have to look for it because here in Europe I did not find any offer now.

Where do I find the fuse yjsaabman mentioned?
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post #13 of 22 Old 05-10-2021, 02:31 PM Thread Starter
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@yjsaabman

Thanks for your answer and help! I sent my last post just the same time you answered :-) Yeah, to change to manual would be an option. It would be my first manual car after many, many years...
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post #14 of 22 Old 05-10-2021, 06:12 PM
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It's s lot work to swap a stick shift. Driveshafts need shortened and lengthened, transfer case linkage needs worked out, clutch hydraulics and hardware, and the pedal cluster is its own challenge. I went that route because I was looking at another auto trans issue in 2 years and about 15k miles. I'd already rebuilt it once and spent over $800, which is cheap because I did a lot of it myself. The swap cost me around $1500 all in, but should be more reliable, in my mind.

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post #15 of 22 Old 05-11-2021, 09:57 AM Thread Starter
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One more question: will Jeep dealership be able to identify a broken TCM inside a 1995 ZJ with a diagnostic tool? I guess they will not have a spare TCM in stock (here in Germany) and before I order it in the US which may take some time, I'd give it a try. I still have a small hope that it is a loose contact or broken wire because the problem came and disappeared at least 10 times in the past 2 months (when outside temperature was changing) so I want to make 100% sure that it is the module and not something else. BTW, the fuse in the main housing was good.
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