aw4 converter lock up question

putting the xj back into service after being down for quite some time.
fixing a bunch of little things, one of the issues i'm having is with the torque converter not wanting to lock up. when i first got the jeep, the converter would randomly unlock; fixed that by cleaning the white switch way up the brake pedal. it worked fine after that. then one day it started refusing to lock up at cruise about 50% of the time. it got more and more frequent until it stopped altogether.

i've cleaned the connectors, cleaned the white switch, changed the fluid and filter, checked the fuses....everything's good. the solenoid ohms out right at 15, so in theory it's good.
what i have found is that when i wired in a tcc override switch, the converter will lock when the solenoid is powered directly......buuuut very slowly. it used to lock up quickly and firmly, almost like another "shift." now it takes around 15-20 seconds from the point i flip the switch until it locks. once locked, it seems to hold-although when i tested it at an idle(VERY briefly), it would not stall the motor. it would drag it down to where it was just barely still running, but it couldn't stall it. not sure if that's normal or not?
any ideas? can a solenoid get lazy, but still kinda work?

my next move is going to be to hook up a voltmeter or led light to the solenoid wire coming from the tcu to see if it's actually getting power when it's supposed to; although the very slow lock up seems not right to me.
for reference, the jeep is an '89 4.0/aw4/242

any ideas?

Get an incandescent brake light bulb and pigtail harness from the junkyard and splice it in somewhere, you can monitor the circuit pretty easily that way

ok, so i did something similar. i hooked a voltmeter up between ground and the tcc wire coming out of the tcu.
i can see that it gets 12.9 volts exactly when i would expect it to-every time. so at this point, it seems that i most likely have a bad converter(seems like a pretty rare occurence), or i have a solenoid that's lazy/only works when it wants to(seems common for these to die).

going to grab a few lock up solenoids out of the wrecking yard this weekend. i'll test/swap them and see what happens.

I was having issues with my lockup on long trips and warm days. I added a transmission cooler and changed out all of the solenoids. It seems to have stopped the lockup issues. The solenoid job is a little messy, but not very complicated.

follow up:
i pulled two #3(tcc) solenoids out of two different low-ish mileage aw4's in the mud and rain on sunday. both ohm'd out good and gave a good solid click when powered.
swapped one into the xj this evening... it appears the torque converter now locks up as solidly as you could ask a 240k mile converter to lock.
it happens quickly and noticeably. so although the original solenoid tested "good", it was definitely tired/lazy/not holding full pressure....something.
i'll probably spend the money for all three new solenoids sometime in the near future, now that it seems there are no trans or converter problems.
lesson learned-they don't have to be "dead" per se, to be malfunctioning.

You can always wire up a TC-lockup switch as well.

Hellbent said:

follow up:
i pulled two #3(tcc) solenoids out of two different low-ish mileage aw4's in the mud and rain on sunday. both ohm'd out good and gave a good solid click when powered.
swapped one into the xj this evening... it appears the torque converter now locks up as solidly as you could ask a 240k mile converter to lock.
it happens quickly and noticeably. so although the original solenoid tested "good", it was definitely tired/lazy/not holding full pressure....something.
i'll probably spend the money for all three new solenoids sometime in the near future, now that it seems there are no trans or converter problems.
lesson learned-they don't have to be "dead" per se, to be malfunctioning.

Click to expand...

IIRC, Cal has said that the aftermarket solenoids are crap. Unless you plan on spending coin on Mopar replacements, better to stock up on JY/used ones. Although, not sure if the new Mopar ones are worth a damn either.

interesting... maybe i'll just stick with my junkyard solenoids for now.
i did wire up a manual lock up switch during my testing. i was going to remove it, but i decided to keep it just because. i put it on a lighted rocker in the old power/comfort switch hole, since i hardwired the jeep into permanent "power mode" last year-just shoved the connector back in the dash.

Here's what I installed on mine:

http://www.ebay.com/itm/Jeep-Cherok...s-TCC-87-01-/151948669164?hash=item2360d8b0ec

It's been a few months and several thousand miles and everything has been fine. OEM sensors and electronics are always preferable to aftermarket, but when money's tight, sometimes this is the only option. I have no complaints yet.

Ok I discovered this thread while trying to figure out my issue. Tell me if this sounds similar to you, 1 to 2 shifts fine, 2 to 3 shifts fine, but after 32ish mph when another shift should happen and I hit more of a crushing speed up around 40 it's almost like I hit neutral. But if I put the Jeep in the 3 position the Jeep shifts great and shifts are firm. Also I don't smell burnt clutch in the fluid. The fluid is a little brown but smells like regular fluid. Does this sound like I may be having a solenoid issue? I had a solenoid go out several years ago so this would seem appropriate on my AW4 in my 97

I researched the hell out of the AW4 while I was having intermittent shifting and lockup issues for a couple of years. The only thing I did that actually helped anything was to change the solenoids. They can test "good" and still be bad, so they're quite difficult gremlins to diagnose. The other fix that a lot of people have suggested is an OEM, Mopar TPS. Apparently, aftermarket TPS tend to be garbage and our picky Jeeps highly prefer OEM sensors.

The solenoid/filter/gasket kit I linked to in post #8 is less than $100 and it's been great for me. Plus, a fluid flush and filter change never hurt.

it *kind of* sounds similar to what mine was doing. at higher speeds/higher loads, the converter not locking up feels kind of "disconnected" from the engine's power. i assume that it's the looseness of the factory converter.
you're going to need to do more trouble shooting, but i would bet it's probably solenoid related.

Ben824 said:

Ok I discovered this thread while trying to figure out my issue. Tell me if this sounds similar to you, 1 to 2 shifts fine, 2 to 3 shifts fine, but after 32ish mph when another shift should happen and I hit more of a crushing speed up around 40 it's almost like I hit neutral. But if I put the Jeep in the 3 position the Jeep shifts great and shifts are firm. Also I don't smell burnt clutch in the fluid. The fluid is a little brown but smells like regular fluid. Does this sound like I may be having a solenoid issue? I had a solenoid go out several years ago so this would seem appropriate on my AW4 in my 97

Click to expand...