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I purchased a 4wd comanche a month ago, and I knew it was going to need repairs done, I had no problem with it. But since then, I've run into a problem that I have done everything within my mechanical knowledge boundaries to fix, yet I can't correct the issue. The truck will idle all day just fine, and if in park or neutral, you can bring it all the way to rev limiter, put it in gear and it will idle fine as well, but give it gas and it will hesitate and stumble so bad it can't even move forward (reverse is O.K., but just ok). I have replaced EVERY. SINGLE. SENSOR on this thing and cannot seem to fix it. I replaced my fuel pressure regulator, distributor, coil, cap, plugs, wires, and stator pickup wire as well. Exhaust is free of restrictions. After replacing my PCM and alternator, the truck only runs halfway decent after all that and a check engine light that came on after I replaced my computer is now off with the replacement of an alternator, but seems to now possess a shifting problem. Now that I have really good power in R, 1, 2, 3 is weaker, I put it in drive and paid close attention to the sound and feel. I noticed that the vehicle jumps (that regular little jump we normally experience when we first put it in gear) in the 1-2 location, very positive in R, the jump is reduced at 3, but in D it is nonexistent, and when I went down the little straightaway of low traffic road in front of my homestead, I heard a bogged-down sound that as I gained speed to about 40, turned into a sound of abnormally high RPM's with no significant gain in speed, as though the truck struggles and can't shift up or down accordingly with the load. Taking off in D it seems that it doesn't start in 1st then work its way up. transmission fluid and filter changed within 30 miles. I am now thinking my problem could be a transmission governor pressure sensor/solinoid or a trans control unit. Would I have both of these or only the governor pressure sensor/solenoid, and could these be my issue?

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You missed the 4wd Comanche in the first post.

Assuming ... And we know how that works ... He has a 4.0, the trouble could be with the TCU (Transmission, Control Unit). Check the fuse and the connector. Is the fluid level still good? How was the fluid changed ... Powerflush or simple drop pan and refill?

Or it's low on fluid, or the Torque Converter is going ... Or, or, or ... A lot of ors left without further details.

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Pete M. I do appreciate the cyber clean up. I ran a norton scan and fix and found some bad things. those lil problems are now dealt with.

 

Rockfrog: Powerflush. fluid level is still full. Call me stupid but where is my TCU located. I can't find a google schematic my model year that shows its location. I know where the fuse is so I might be able to follow its wires to the TCU

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If your truck is a 4.0/auto as we think it is, the TCU will be under the lower dash panel (the part with the ashtray) on the passenger side. You'll have to take it off to get to it. I've never heard of them going bad but I suppose it's possible. How much metal/clutch material was in the transmission pan?

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Having had the truck for just a month, then having the trans powerflushed ... Could possibly be the root of the issue, the AW4 does not tend to respond well to them. If there was a regular service schedule prior, yes, but if none, it may have caused the issue.

But, check the TCU, fuse, and wiring first ... Located as indicated above.

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Pete M. I do appreciate the cyber clean up. I ran a norton scan and fix and found some bad things. those lil problems are now dealt with.

 

Rockfrog: Powerflush. fluid level is still full. Call me stupid but where is my TCU located. I can't find a google schematic my model year that shows its location. I know where the fuse is so I might be able to follow its wires to the TCU

 

You shouldnt rely on norton, It in itself is almost a virus.

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If your truck is a 4.0/auto as we think it is, the TCU will be under the lower dash panel (the part with the ashtray) on the passenger side. You'll have to take it off to get to it. I've never heard of them going bad but I suppose it's possible. How much metal/clutch material was in the transmission pan?

no more than what I would consider normal minscule amounts of particles. color was not abnormal, just that used red color, but the fluid was trash and felt way thicker than normally used trans oil

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If your truck is a 4.0/auto as we think it is, the TCU will be under the lower dash panel (the part with the ashtray) on the passenger side. You'll have to take it off to get to it. I've never heard of them going bad but I suppose it's possible. How much metal/clutch material was in the transmission pan?

no more than what I would consider normal minscule amounts of particles. color was not abnormal, just that used red color, but the fluid was trash and felt way thicker than normally used trans oil

 

 

This makes me think that someone at some point dumped in some of that "transmission fix" garbage.

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after removing the lower half of my dash, I see no TCU under the passenger side dash. just black plastic guards for my heater core. Looked at driver side just to be sure and nothing there either. I don't have a Renix jeep if thats a Renix thing

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after removing the lower half of my dash, I see no TCU under the passenger side dash. just black plastic guards for my heater core. Looked at driver side just to be sure and nothing there either. I don't have a Renix jeep if thats a Renix thing

 

Again, what - do - you - have?? If it's not a Renix, and you have a Comanche, then you have a 91 or 92 Comanche. And they had the TCU in the same right lower dash location as the Renix models.

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I do apologize for the multiday hiatus, but what I found my problem was that the transmission itself was bad for it burned up on my way home from the tag office. I do thank the fellow jeepers who spent their personal time giving me advice for my issue. 

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My friend had almost the same problem in his 2 door XJ. In park could red line all day. In drive could only hit 1500-2000rpm and just stopped. Wouldn't rev higher. Ended up being a clogged fuel pump strainer in the tank. Replaced with new and has run great for the last year and a half. For anyone that may run into a similar situation

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I HAVE FOUND THE PROBLEM, AND EVERYTHING I DID WAS WRONG! Two months ago when I replaced my ignition switch, I had to take the dash panel off to get to it easily, and I left it off while tinkering with a no turnover in park (which happened to be the neutral safety switch) and what I didn't realize was that I unplugged my transmission control module (which I had no idea what it was at the time)which is attached to the panel. With it unplugged, the transmission couldn't function properly on its own which led me to spending 2000 dollars on parts I didn't need and many hours trying to solve problems that actually weren't even occurring. I had a friend on his way to my shop to help me put a new transmission in when for some reason I just saw the plug dangling from the dash, which led me to figure out what it went to, I remembered that the aquamarine color was on a little module, which I then located on my lower dash panel that I set aside awhile ago, Plugged it bag in and the truck runs like new again (transmission fluid a little pale from the extreme temperature after crawling home in first, will change). MORALE OF THE STORY is that if your transmission is having an untraceable problem like mine, check your transmission control module, for its like a little computer but specifically for the transmission on automatics. Have fun and good luck fellow Jeepers!

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MORALE OF THE STORY is that if your transmission is having an untraceable problem like mine, check your transmission control module, for its like a little computer but specifically for the transmission on automatics.

 

Why didn't you check the TCM first as advised? Many times.  :hmm:

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