Sorry for another AW4 Lockup question, but I haven't seen these symptoms anywhere else.

99 Sport, 4wd (1st XJ 4wd for me!)

- Shifts great from 1-OD
- Does not do the final downshift (TC Lockup, I'm assuming)
- If I disconnect the TCM while cruising (triggering limp mode) it will do the last downshift and rpm's will drop.

I...
Have changed TPS to a OEM
Have adjusted the TV cable
Have checked the brake light switch. Brake light works fine, goes on and off like normal.
Have cleaned the black and gray connectors near the passenger firewall

Questions:
-In limp mode and D, does the AW4 indeed shift to OD with TC Lockup? From what I've read, I thought it just went into OD.
-Could this be NSS?
-Any other sensors this could be?
-Could brake light switch be defective preventing TC Lockup, but allowing brake light to function?
-Can I presume that all shift solenoids and internals are fine since between regular mode and limp mode I can hit all gears?

Thanks y'all




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I'd kinda like some input on this too. I am having the occasional "stuck in 3rd gear" problem. It comes and goes, and seems to happen just on the really hot days. I tried the cable adjustment, and it seemed to work for a couple days because the thing was way out of adjustment. I also tried to disco the TCM and it didn't let me shift through the gears manually. As in it still wouldn't shift through every gear into lockup. I did this step after my XJ was already hot, and it was a hot day also, so I dont know if it was still too hot or what. I dont have a trans temp gauge so I dont know if heat is the issue, or if heat even contributes to the stuck in 3rd issue.
What about solenoids on/off depending on gear? Would there be one to check? or since I only have issues with one gear, is it not the solenoids?

Wasn't trying to take over the thread, just looking for more info for both of us....

 

Have you ohm'd the solenoids yet? 2nd gear is no.1 and no.2 Solenoid ON, 3rd gear is only no. 2 ON... so if you're actually getting second and not 3rd then the solenoids must be working, but maybe the gear shift is off, via the NSS. Especially since it's not working manually either.

I just ordered a new NSS... I know they can be cleaned, but mine broke just time taking it off so I'm just starting from scratch.

 

Don't quote me on this, but I believe it goes 1-2-3-lockup-4. So if you're not getting that final shift, I believe it's 4th you're missing. It sounds to me as if electronically it's not calling for 4th gear, so you can go ahead and rule out the transmission/valve body. So that leaves one of 2 things. The throttle valve cable (which you've already adjusted) and the TPS (which you say you've already replaced).

I've been in this same situation. Long story short, I replaced the TPS with one from a junkyard and it worked. I tested, and tested, and tested, and replaced stuff, and did everything possible. I had multimeters hooked up to watch the solenoid outputs, checked the TPS range with an analog multimeter, I rebuilt the valve body and installed a shift kit, I replaced the TCM, traced wires, checked continuity, everything. The worst part is that the TPS tested completely fine, every time. A junkyard TPS solved all my problems, so I stuck with it.

 

Lockup in third seems to depend on the year and speed. 4th gear has both solenoids off, so it's much less likely to be a bad shift solenoid. With the TCM unplugged, you do not get t/c lockup. Check fluid level, and test the TPS with a meter, especially the ground wire to it.

1st - Solenoid 1
2nd - Solenoids 1&2
3rd - Solenoid 2
4th - NO solenoids
t/c - solenoid 3

 

With the TCM unhooked it will stay in 4th when you have it in D and the converter can't lockup.
Possibly but I doubt it, mine is bypassed right now and it shifts though all the gears and locks up fine.
Most likely something is going on with your shift solenoids or a wire is shorted somewhereThat is possibleNo

 

Thanks for the input guys. So since I'm a bit short on diagnostic time, I threw a switch on the A solenoid to manually power it off... and it works like a charm... getting all gears plus lockup. Not sure why it's the A solenoid though because if 3rd gear is the B solenoid, then shutting that one down should have put it in 4th gear. Anyway, tried that and it didn't work but A did... unless the wires to the TCM are somehow crossed...

 

It's possible the TCM has a blown driver too. It's rare for the TCM to be the problem, but it does happen every once in a while.