Unlikely

Executive Summary:
1989 Jeep Cherokee Limited 4x4 Automatic - Reverse gear isn't doing much so I'm looking for next steps to test/verify.
I'm working Cruiser54 Renix refresh steps, making great progress (slowly, due to this being a side project.) Idling well, running decent, and shifting properly in forward drive. Limited testing, still not over 45 mph, and under 10 miles per test. (It wasn't shifting until 3 to 4k previously, used to idle high, now those issues are testing and working normal.)

Now putting it in reverse, it barely moves. Moving from Park to Reverse, I feel a slight "bump" as it engages, but then it doesn't do much. Increasing the RPM doesn't help either. It does this both cold, and after being driven for 15 minutes in non-highway driving.

Details/History:
Transmission wasn't shifting correctly. Engine revving to around 4k before downshifting. Inconsistent at best.
Read other trans threads: Changed trans fluid (drained via drain plug), new Dex/Merc fluid. Throttle Position Sensor (TPS) changed. Adjusted TPS with multimeter after getting reference voltage, and 83% on the money. Left meter connected while doing final tightening of TPS. (Per videos by Nick...). Spot on the 83% reference. Disconnected battery and reset computers to allow relearn for TPS...

Drives and shifts in reasonable ranges, barely feel the shifts moving from start to 45 MPH. Feels like "normal" shifting so far. (Overall excellent progress, since it was so out of range.)

Reverse is another story: If totally stopped, moving shifter to reverse I can feel a minor "bump", like something is engaging. That said, giving some throttle and very little reverse action. IF I try to back up a slight incline (my driveway), it can't do it.

Additional symptom: I have never tried the all wheel drive/4 wheel stuff. Moved that level through the options when working on the reverse symptoms. No changes in terms of reverse, as expected. (I didn't drive more than 100 yards in any other position, was wondering if that might change trans symptoms, made zero diff.)

After putting the all wheel shifter back to original position, the "Part Time" light stayed on. Not sure how to get it back to original "Off". Not sure if any of that stuff is working on this Jeep.

Still more refresh stuff to do: I haven't yet refreshed the electrical plugs for trans related wiring, but I read that reverse is unrelated to any electrical connections. (NOT verified, which is why I'm mentioning it in case my info is wrong.)

I skimmed this forum, reading every thread related to Transmission/Reverse and/or shifting that I could find, and first 35 pages of the NAXJA thread titles, to understand more about similar issues and how they were resolved.

I used this thread where Cruiser54 recommended changing fluid, then replaced the TPS and computer reset after testing/figuring out the voltages were messed up on the original TPS.
https://www.cherokeeforum.com/f2/rev...oblems-249556/

I see he recommends "repeat as necessary" for fluid replacement. Wondering if I should drain fluid multiple times as I've read a drain only gets a portion of the fluid changed. Not sure since it's driving very well in forward, if that means fluid refresh isn't helpful at this point. (I assumed it would do another drain/refill in a month or two after resolving additional issues UNLESS it would apply to my current issue.)

Two steps forward, now I need reverse.

All ideas/troubleshooting tips/links to info welcomed!

lawsoncl

Did you inspect and adjust the throttle-body to transmission cable (often incorrectly called a kickdown cable)? It controls the hydraulic pressure in the transmission, which affects the shift firmness. If it's disconnected or very loose, you'll get very soft shifts and sometimes won't even move in first or reverse. Having it too loose for too long can burn up the clutches and bands due to slipping.

Aside from that, the reverse gear is purely mechanical and not controlled electronically. I think your electronics are working, since you said it's shifting normally in the forward gears otherwise.

Unlikely

No, not even aware of the details of that cable. The forward shifts are all working as expected, but now I'll look for that cable.

If it was loose/disconnected, would first/forward work and shift as expected? Is it possible to have forward work well, but the cable only be a factor for reverse?

Off to do some research. I appreciate your response. Even if that is not the issue, I'll learn something. All other input/links appreciated.

Unlikely

I found a couple videos on YouTube for adjusting that cable.

It ended up in the same place after resetting, then pushing accelerator cable all the way down.

I drove it after resetting, same issues.

All other ideas welcomed.