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AW4 TC Not Locking Up


NAXJA Forum User
Charlotte, NC
Have a 94 xj with 4.0/AW4 and since I did 1-ton swap the torque converter doesn't seem to lock-up. Per every calculator I've used I should be doing about 2300 rpm at 65 with 37/5.13, but I'm doing about 2650-2700 rpm. It get's into 4th but the TC doesn't seem to lockup.

My mph gauge is accurate per GPS.

Already checked the brake switch under the dash, trans cable adjustment, and checked/cleaned the NSS. I'll check the TPS this weekend, but is there anything else besides the TPS and the solenoid I should be looking at?

Trans fluid is fresh and clean too. No brake dragging either.
Brake switch, TPS, NSS, solenoid and/or wiring are the usual culprits. TPS will tend to mess up the shift points too.

An easy O/D check is lightly tapping the brake with your left foot while cruising steady at highway speed. If it's not jumping up a bit, then you're probably not locking up. You're using 0.75 in your calcs right? A pre-1991 AW4 had 0.70.
You're using 0.75 in your calcs right? A pre-1991 AW4 had 0.70.

Definitely using .75 in the calculations, that's of the first things I checked. All the other shift points seem to be normal, it's just the TC lockup not happening. Trying to isolate every external possibility before dropping the pan. If I do that I'll just do new solenoids and a sift kit just because I'm in there already.

I do know that the wiring connections can come off the solenoids and people typically make new connections if that happens
You can measure the solenoid resistance at the connector in the engine bay, or at the TCM itself.

Should be the black electrical connector by the trans dipstick tube. 4 blades on top, 3 on the bottom. The first 3 of the top are to the solenoids. 13 ohms +/-3.