cruiser54

TV cable adjustment:

https://www.cherokeeforum.com/f2/free-quick-fix-41821/

67 GMC

Thanks for the check TGordon!

67 GMC

Thanks-I did this a while back.

67 GMC

Update for today-I took the trim panel off where the TCU is attached. I was amazed that while the TCU is bolted to a metal trim piece, the trim piece itself it only grounded when the two screws near the courtesy lights are attached. The courtesy lights have two wires and don't ground this strip. I attached a wire to the metal strip to ground this better. Took the Jeep out tonight, it shifted fine up and down the street until it warmed up and then it would just rev and wouldn't get out of first. Disconnected TCU and went home in limp mode.

So I'm thinking its either a ground that gives out when it's warm or something in the transmission that changes onces the fluid gets hot. That's why I'm leaning towards the speed sensor or solenoids being faulty or bad connections. I'll attach a ground strap to the transmission tomorrow to try that out. I'm running out of ideas. I did change the burned out light bulbs in the cigarette lighter, ash tray and the heater controls so at least it looks nice and bright at night.

DFlintstone

Without reading back through the whole thread, I just wanted to mention that there are wire plugs sort of back from the dipstick where i believe the solinoids plug to the harness. You might want to check & clean them if you haven't been there already. Cruiser might have mentioned it's the grey one that goes to the tranny, I'm not sure though.

Radi

That is a common way for a solenoid to fail, sticking once it warms up.

67 GMC

I'm thinking this might be it. It works perfect until it warms up. Also works in limp mode. Any chance it could be a bad electrical connection that once warms, loses connection? Would an erratic solenoid show up on a dealer diagnostic test? Don't mind paying the money to get the problem fixed.

cruiser54

Has it started doing it again?

DFlintstone

If I had a spare TCU, and hadn't checked the connections between that and the solenoids...I'd probably check and clean the terminal connections first there behind the dipstick, and then try the other TCU. Then if there was still a problem after all that, Radi's experience with the solenoids .......I'm in over my head here!

67 GMC

BIG UPDATE: I think it's fixed for now. I used my spare TCU, hooked up a ground to it, and ran the harness to it and hooked up my multimeter to C3. As I drove in the morning to get gas, I could see the regular pulse of the speed senso (0V, 5V, 0V, 5V etc). When you go faster, it pretty well read an average of 4 V since the meter can respond that quick. Trans shifted flawlessly to the gas station (about 7 minutes away). Turned off engine, got gas, turned engine back on and drove slowly out of gas station. No pulse from speed sensor! Wouldn't shift from 1st again. Disconnected TCU, went home in limp mode. I'm thinking it was a bad speed sensor. Went to look at how hard it would be to change it and started moving crud encrusted wires around. Noticed a spot where the wire conduit has come apart. Moved that back into conduit. Started the warm jeep back up, speed sensor readings are fine (0V, 5V) etc. Transmission shifted perfectly up and down. So, I think that is/was the issue. I still have a lot of dirt around those wires on the trans but I'm thinking it was a short to ground once the trans case got hot enough. Took on secondary highway for 30 minute drive and all ok.

So, now my only issue left is the lack of kickdown when you floor it. If I give it medium pedal, it will accelerate decently but if I mash down, I don't get an appropriate response. Could this be the TPS adjustment now or is it the mechanical throttle linkage? I'm happy enough right now to drive like it is but it will be bothering me eventually and I'll have to fix it!

Hats off to Radi, Dflintstone and Cruiser for the help and support. Next time I won't hijack the thread either.

cruiser54

Notice what is says in my signature? RCBRC? You are a living example of tenacious application of that philosophy. My hat is off to you.

67 GMC

Amen-I was talking to a friend about this. You have to choose a path when you start with a repair. The first path assumes there is something wrong on the way to the part that is preventing the part from working properly but the part itself is not the issue. The other path, you assume that everything except for the part is working correctly. Sometimes, it takes longer to go the first way put it is definitely less expensive and you don't end up with lots of parts sitting in boxes on your bench.

It's also the Sherlock Holmes philosophy, "Once you've eliminated all other possibilities, what ever remains, however improbable, must be the truth"

I started with a Jeep that wouldn't start periodically. Sounded like a bad CPS but you kept on sending advice on grounds etc. Saved me from having to install a CPS when it was the dipstick ground.

I bow to the master.

cruiser54

Look at it this way. If you had purchased and installed the speed sensor, your problem very likely would have been fixed due to you plugging the new one in and you wouldn't have been the wiser. Crap!! I'm sure that happens all the time.
You've made some good improvements and nipped alot of problems in the bud.

Radi

Nice work! And the price of repairs wasn't bad either

67 GMC

Thanks-I learned a lot along the way as well. Can't imagine trying to do this without the forum.