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Aw4 Transmission Delayed Engagement


NAXJA Forum User
I have an '00 Xj 4.0 with an aw4. The transmission is not original to the jeep since i converted from 2wd to 4x4. The tranny supposedly had 123k when i installed it 6k miles ago. Basically after installing the transmission i filled it up with dex atf and then started the jeep and tried to drive it and there was barely any output power out of the transmission. I tried to drive the jeep around my driveway and the jeep would barely move and would only move when i held the rpms around 2k or higher. Since i had never installed a transmission before, it never dawned on me that the torque converter didn't have enough oil in it. Finally after shifting the transmission from drive to reverse multiple times, the transmission started to move the jeep and eventually the torque converter must've sucked all the oil out of the transmission because i then had to add another 4 quarts or so. The reason i'm writing all this is just to give some context and also say that when i was trying to move the jeep initially before the torque converter filled up, it smelt like i was burning the tranny fluid.

Anyhow that's the backstory, here's my problem #1... about 5k miles after installing the transmission, my transmission no longer engages as quickly as my other XJs. When i first start it up in the morning and i go to put it in drive or reverse, it takes a little bit before the transmission actually engages. It doesn't even have to be cold to do it, its just slow to engage into gear no matter if its been sitting all night or been driving all day. It might be slightly worse when cold. From what i've read this is called "transmission delayed engagement" and there can be multiple causes such as worn clutches and solenoids. I tested the resistance in all three shift solenoids at the electrical connecter in the engine bay, and they all had around 13 ohms. Could the solenoids still be the culprit even if there is no CEL and they passed the resistance test?

Problem #2 When driving down the highway at a constant speed for an extended amount of time, the transmission likes to "come out" of overdrive, almost like the torque converter unlocks, it doesn't downshift into 3rd it just acts like its between gears but as soon as you step on the gas it shifts back into overdrive or the torque converter locks up again. Sometimes when it acts up, it keeps going in & out of overdrive which makes jeep start jerking but as soon as you change throttle position it stops. This only occurs when you hold the throttle at a constant position. It doesn't seem to matter how fast or slow you're going just as long as its in overdrive.

I'm not sure if Problem #1 & problem #2 are related but i wanted to give the full picture. What do you guys think is going on?
If you still have the slow engagement dropping the shifter into (1-2) instead of (D), it's not the solenoids. Is it just the initial engagement? Is it shifting firmly or slow between gears once rolling? Have you tried adjusting the throttlebody cable?

Problem #2 sounds like a bad throttle position sensor (TPS) to me. They do wear out and get a dead spot which can trick the trans computer into unlock the t/c or shifting at the wrong time. Another possible cause (but I don't think that's the case here) would be a bad brake pedal switch, which is one way the trans computer knows when to unlock the t/c.