Hey everybody. I was driving to the airport the other day, and my tranny upshifted while on flat ground at 55. You could hear the jeep revving out pretty high, so I slowed down. I dropped down to about 45 mph, and then it shifted into 2nd. I pulled off the highway, shut the jeep down, and checked out what I could see (which wasn't much), but I could see no obvious problems from the outside. it was still upshifting itself into 2nd the whole way, and a few times it would just slip out of gear entirely until I coasted down to about 20 mph. I would think this means my trannies toast, but it only has 123k on it, and hasn't shown one little ounce of tranny trouble before.

Anyone ever have problems like these? What'd you do to troubleshoot?

 

start with fluids... if checking tranny fluid, have jeep running and in N. idk... somebody will have something more helpful...

 

Sometimes the Throttle Positioning Sensor can cause your trans to act up. You should probably test that too.

 

It could be vacuum related. If I'm not mistaken the shift points are determined by vacuum and trans fluid pressure.

 

1. check fludi levels
2. check voltage on TPS
3. check the TCU see if anything looks bad there.

if all those pass inspection id say yes the AW4 is going/gone.

I just replaced mine last weekend.

 

The shift points are determined by the computer. It is an electronically controlled transmission.

 

There are still things internal that control shifting.

But I don't wanna argue with you. You'll drone on and on til everyone agrees you are right.

So you win.

 

So fluid level has nothing to do with it huh? I find that hard to believe.

I am with almost everyone else, start with the fluid level

 

The internal things would be called valve bodies and solenoids which are controlled by the computer.

 

Yes definitely start with the fluid, if you don't have enough your trans won't shift. Personally I would probably start with a fluid and filter change if you haven't done that in a while. There is also a fuse for the TCU my brothers Grand Cherokee blew that fuse and the symptoms are similar to yours.

 

1. Ensure fluid is at correct level, red in color and doesn't smell burnt. Checking fluid is ALWAYS job #1. Always.

2. The THROTTLE POSITION SENSOR is directly involved with shifting characteristics and needs to be tested!!!! You will need a manual and a meter (analog best).

3. Follow the FSM for disconnecting the TCU to see if the problem is electrical or mechanical.

If fluid checks out, you really gotta focus on that TPS. I have repaired many an AW4 with shifting problems with a new TPS!

 

Thanks everyone I'll update everybody when I get back to the jeep.

 

Edit: double post

 

the aw4 automatic is controlled by vacuum and the tcm when the tcm is out it doesn’t slip bad at all it just only goes into first and third gear because the computer controls the second gear solenoid, and the fourth gear solenoid, I know this because my fuse that runs the tcm popped and it would drive fine until it tried to shift into second and then it’d jam itself into third

 

13 year old thread revival.....