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transmission problems questions

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I am in East TN, 444 miles from home.  I have no reverse, it trys to go forward in neutral, it changes gears ok and seems to be ok in forward gears,  The part time light flashes on  and off when in 4 wd high.  She has plenty of fluid,  What are ya'lls thoughts?  I have a great mechanic back in FL.  I am thinking about driving it back for him to work on jt.  Could this be a computer issue?  What years computers are compatible with my 88 Laredo 4wd 4 liter automatic.?  HELP  Bill

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when your moving it to reverse see if it trys to catch at all. i had a issue in my first 88 with no reverse i changed the fluid to Valvoline max life dex/mec which is a universal fluid if you have ever took the class from valvoline oil. added 1/2 a bottle of lucas and changed the fliter. seemed to work for me. on the tcm reverse would still work if it was bad you wouldn't be able to shift through the forward gears unless you manually did it.   

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Everything lines up properly.  What harm can I do driving home?  It could be interesting with no reverse.  Could it be a linkage issue?  I just had a long block installed.

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So long as your transmission is behaving normally while in forward gears, then I don't expect that it would damage anything, although I can't really comment without actually knowing what's going on. If it seems to be slipping or grabbing more than one gear at a time, then that's a problem.


What I'm saying about things not lining up is based on experience I had after recently removing the shifter. I didn't quite get the panel lined back up again in the console, and so the shifter indicated R when I was actually in Neutral, N when I was in Drive, etc. The transmission's reverse was somewhere between Park and indicated reverse. It was a while before I noticed anything was wrong, because I very rarely actually looked at the shifter while I was using it.

If whoever swapped in your long block pulled the engine and transmission out as a unit, your shifter may also have been removed to disconnect the shift cables from it, and may not have been put back perfectly. Even if the transmission stayed in the truck, the shifter is often removed for better access to the top bellhousing bolts. 


Maybe describing what happens in each shifter position will help someone else answer whether or not you'll damage your transmission by driving as is.

Don't look at the gear indicator while you're shifting, feel for the shift detents. Start in Park with your foot on the brake pedal and then go through reverse, neutral, drive, "3" and "2-1". Use a bit of gas in each position to see if the truck moves. Do your reverse lights come on at all as you move through gears? Can you leave it in a position with the reverse lights on and attempt to make the truck move? Does Park actually lock the transmission and prevent the truck from moving?


The gear indicator is a few pieces of plastic that are pushed around by the shifter, and has nothing to do with what's actually happening at the transmission end of things.

If the linkage is slipping, you'll likely run out of shifter travel before hitting all the gear detents. Remember that there are six of them, and that 2-1 is one position, not two. If it's badly adjusted, you should still be able to move between gear positions, but it won't have much to do with what the gear indicator says. The detents ("clicks") you feel when you shift gears are happening inside the transmission, not at the shifter. Again, it sounds to me like you're simply passing over reverse and hitting neutral instead of reverse, and then you're in drive when you think you're actually in neutral, and then in third when you're actually in drive. Third behaves exactly the same as drive until you're up to speeds when overdrive would be useful.

I'm not sure the linkage is really all that adjustable, though. IIRC, the cable simply pulls/pushes against a lever on the side of the transmission, and in reality the only variable is the length of the cable, which shouldn't change. I'm 300 miles away from my MJ, so it's kinda difficult for me to crawl under and check.

Also, the tranny computer only takes care of shifting between forward gears and torque converter lock-up. It also reads shifter positions off the transmission, not the shifter.

Again, the shift indicator has very little to do with what gear you're actually in, and it's one of the few things that can go wrong. The only other things I can think of would be a broken shift cable (not the case because you're shifting) or else something is seriously buggered up inside your transmission such that it's grabbing gears when it shouldn't be (i.e. drive in neutral).

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