thank you all for your suggestions so far!

i'll try testing it without the tcm to rule in or out electrical...

but where do i pull the fuse/relay for the tcm?

is it in the junction box beside the battery?

it's a rhd model.

Yea, it should be in there. I think it's fuse #5 in the box by the battery (FSM doesn't specify RHD/LHD for that, so hopefully it should be the same?), not sure which relay, but it should be labeled in your owners manual. It should be easy to tell, in drive you will get 3rd and in low you will get 2nd. Reverse should give reverse.

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2005 Jeep Liberty Sport CRD 4x4 278k

ok so i pulled the tcm fuse in the junction box.

i was able to put it into 1st , 2nd and reverse manually with the shifter.
it drove ok in 1st and 2nd.
when i put it into reverse it was taking a while to shift into reverse but if i left it a couple of seconds it would start moving backwards.
it didn't seem to have much power when in reverse though..i was trying to reverse it up an incline to park it up, but it struggled. when i put the fuse back in and then reversed it had more power and was able to reverse up the hill better.

however the good news is that it didn't stall at all when i was driving forwards and backwards...that's a good sign right?

so does this point at electrical problem? sensors or maybe something in the valve body or solenoid?

Sure sounds like an electrical problem, but the issues using R with the TCM unplugged is a bit concerning. I'm sure there is a spec in the FSM for checking pump pressures.... that would be my next stop since it's been established the transmission "generally works."

Have you checked the harness connection to the solenoid pack/valve body?

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U.S. Army Retired

the harness connection to the valve body looks fine and is intact and securely latched in.

i guess the next port of call will be to drop the transmission pan. maybe a new valve body with new solenoid might be worth investing in? in case some metal shavings got through into it.
they're expensive though..i see a couple of cheaper ones on ebay but they're from china so i'm reluctant to try them.

my biggest fear is that there is something wrong with the new pump or torque converter...neither i or my mechanic have the appetite to drop the whole transmission again in a hurry

i started up the jeep again tonight (with the tcm fuse installed)...and just went from park to drive but kept my foot on the brake without going anywhere...lots of grinding noise underneath before it stalled and died.

I definitely would not continue to run it except in direct pursuit of repair. Every second an automatic is misbehaving equals a much shorter life.

I would not rely on visual inspection of the wiring harness - I would take it apart, make sure the terminals are straight and in position, and do as much as you can to inspect the harness for damage or abrasion. Check the cooler circuit for obstructions, drain the fluid and look for particles, do a pressure test on the box to be sure the pump is working. No joke, you might consider towing it to Aamco. They aren't great, but they have a lot of tooling and a lot of information to get to the heart of the matter quickly. With a commodity transmission like the Jeep has, they should have no problem making a reasonably accurate determination. I'm not sure if it's still true, but they used to provide a cheap diagnostic rate which was quite favorable.

Yea, the no power in reverse doesn't sound good, although I haven't really tried that (I think the TCM does have some way to Derate the engine...).

The not stalling out is a good sign, but it could be a problem with first gear too... (first gear is not engaged at all when the tcm is disconnected, you'll have 2nd and third) Grinding noises are not good at all... There's not really anything in an automatic transmission to grind unless something really bad has happened. Although perhaps the sound isn't transmission, don't know. Makes me worried that the metal in your pan last time wasn't from the pump. Yea, you really shouldn't drive it at all until you've sorted it out.

Now for some good news! I've been studying the diagrams! The low/reverse solenoid also controls the converter lockup. I don't think you need to replace it or the valve body, but you do need someone who can go through the valve body very carefully and make sure it's spotless and everything moves freely. (and not mix up springs, put valves in backward, loose the check balls, etc.) Also there are check balls loose when you remove the valve body. You need to be very careful and remember where they go (they will just lay in the valve body unless you tip/drop it). Really someone who knows what they're doing needs to do this (or at least someone who understands what they're getting into if they mess up).

There's a valve labeled S.S.V. (Solenoid Switch Valve) that directs flow either to the L/R clutch or the Converter Clutch. If that's jammed or not getting fluid pressure where it should when the transmission tries to engage the L/R clutch it will lock up the torque converter instead. The L/R solenoid only actually engages in 1st as you're starting off, it's completely hydraulic in reverse, so it should only be stalling in 1st. That would explain the stalling, it doesn't explain the slow engagement and lack of power in reverse. That could be a solenoid leaking (the Multi-Select solenoid) or possible the Low/Reverse switch valve (not the S.S.V.) but it doesn't explain it getting better when you plug in the fuse. I'll just pull the fuse on mine and see what it does tomorrow. It seems unlikely, but maybe that's normal.

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2005 Jeep Liberty Sport CRD 4x4 278k

thanks foxmiles for all that info. i'll definitely look into it all when i start getting work done on it again. i was there when my mechanic pulled the valve body off the first time when he dropped the transmission pan. i remember him having trouble getting it loose so i don't know if he damaged it somehow because when i watch the videos now on youtube they say it should come off easily enough once the harness is disconnected and the correct bolts are undone...but hndsight is a wonderful thing! at that point i didn't even know what a valve body was!

however if he had damaged it that time, then that doesn't really explain getting a weeks driving out of it without any problems...

anyhow i probably won't do anything with it from now until the new year at least. i'm starting the engine every couple of days just to keep it ticking it over. (i had filled it with a full tank of diesel the day before it died!)

in the meantime i've bought myself a 06 model 3.0 crd grand cherokee laredo with 170k miles to get by and get into and out of work. i had 2 wj grand cherokees previously so i'm used to them. this has an oil leak at the back of the engine (not the turbo seal) and the transmission seems a little clunky at low speeds in traffic but as long as it holds up a little while to get me by i'm happy enough.

despite the laredo's greater comfort i still really miss my little tractor!