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Very strange cold shifting problem with AW4

Muad'Dib

NAXJA Forum User
Location
Bend, Oregon
Hello all.

Wondering if anyone has come across this particular issue and found a resolution. Ive found some threads searching that are similar but it seemed no resolution was found.

What happens is that the Transmission when cold will seem to stick in 1st gear. The way I like to describe it is like when you put the shifter in the 1-2 position and it takes almost redline to get it to shift to 2. This same thing appears to occur when in Drive. Interestingly especially on a cold morning when starting the Jeep the transmission will make a whining noise.

After driving the Jeep through a few stops and it exhibiting the problem it will go away and start shifting fine. I thought it may be a pump issue, but part of my troubleshooting has included a flush of the transmission using the return line disconnect procedure and fluid was flowing out the return just fine...

Any ideas on this one? Could this possibly be a NSS issue even though there are no issues with reverse or backup lights? What about solenoids?

I would hate to go through the effort of rebuilding a replacement when its something I'm overlooking. And just an FYI its not the TPS as that has been replaced with multiple known good ones. Grounds have all been gone through multiple times as well.

Thanks for any insight you may have.
 
My 96 seems to hang in 1 and 2 longer than usual when
cold, although not as bad as yours. After a couple minutes
of running it shifts normally. I attributed it to perhaps a
worn TPS or old fluid, but after reading your post I don't
know...?

A guess would be maybe a sticking 1-2 shift solenoid...?
 
What trans fluid is in it ?

Grab your FSM and follow the trouble shooting charts and diagnostic testing.
 
Put 1/2 of a pint of Trans-X in the Tranny fluid and run it for 1-2 hours, let it sit overnight, drive it some, forward and reverse, then drain all the fluid you can and top it off with Dex III and 1/2 pint of Trans-X. It will slowly dissolve baked on varnish off the valve body parts that are sticking when cold. May take 2-3 times doing this to get it running trouble free for several years again. I have done this to many transmissions for decades, 3 AW4s for over 10 years. Much cheaper than replacing the valve body...which can clog it again in a new valve body if the varnish is not removed from the entire internal housing first.The varnish gets sticky in cold weather, and settles out of solution in the valves when cold.

Hello all.

Wondering if anyone has come across this particular issue and found a resolution. Ive found some threads searching that are similar but it seemed no resolution was found.

What happens is that the Transmission when cold will seem to stick in 1st gear. The way I like to describe it is like when you put the shifter in the 1-2 position and it takes almost redline to get it to shift to 2. This same thing appears to occur when in Drive. Interestingly especially on a cold morning when starting the Jeep the transmission will make a whining noise.

After driving the Jeep through a few stops and it exhibiting the problem it will go away and start shifting fine. I thought it may be a pump issue, but part of my troubleshooting has included a flush of the transmission using the return line disconnect procedure and fluid was flowing out the return just fine...

Any ideas on this one? Could this possibly be a NSS issue even though there are no issues with reverse or backup lights? What about solenoids?

I would hate to go through the effort of rebuilding a replacement when its something I'm overlooking. And just an FYI its not the TPS as that has been replaced with multiple known good ones. Grounds have all been gone through multiple times as well.

Thanks for any insight you may have.
 
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