Weird shifting and no power

[itsa svx]

Hello - Having a weird issue with my jeep that I could use some help figuring out.

If I put it in Drive it has no power when starting off like it is starting in 4th gear. I can start off in 1-2 then manually shift up and it is fine power wise but occasionally after a short ride it will just feel like it has no power and won't go over about 35mph. If I pull over and turn it off for a minute then start it back up it will run good for a while then repeat the issue. I was thinking the TCU was bad so I swapped in another but no change. I verfied all fuses are good - even the positive in-line to the TCU and it has power at the harness into the TCU. No Check Engine light on...

Thinking of maybe a bad TPS but not sure it could cause this much of an issue.

Any suggestions would be greatly appreciated.

[4.3LXJ]

If you ca do it manually, but not automatically the solenoids are not working. But from your description they work some of the time. So I think you can rule that out. The first thing I would do is check connections and grounds

[olds-cool]

Sounds like something is throwing it into limp mode.

[89Laredo]

Check the Tps.

[itsa svx]

Ok - Checked the TPS and it was reading good. Threw a new one in just to be safe but didn't fix the problem of it wanting to start off in 4th.

Any other ideas of what I should be checking for?

Anyone around Fredericksburg, VA that would be willing to take a look and offer an opinion?

[Mudderoy]

Ok - Checked the TPS and it was reading good. Threw a new one in just to be safe but didn't fix the problem of it wanting to start off in 4th.

Any other ideas of what I should be checking for?

Anyone around Fredericksburg, VA that would be willing to take a look and offer an opinion?

It's a stretch, but have you tried disconnecting the electrical connections to the transmission, clean them and then connect them back up?

Also there is a transmission model under the dash (I believe) that could be bad or not making a good connection to the harness.

[BlueXJ]

Sounds like a sticking solenoid on tranny to me. When one solenoid is engaged no other can be engaged at the same time, thus your 4th gear solenoid is getting sticky and needs to be replaced. The manually over-riding the 4th gear puts a direct power to each manually engaged solenoid and the 4th gear one is receiving no power and another one is so it is forced to disengage. HTH

[89Laredo]

. When one solenoid is engaged no other can be engaged at the same time,

S1 and s2 are powered for 2ND gear. I used to have switches hooked up.

article I found
http://mikestrawbridge.com/blog/2011/09/aw4-troubleshooting/

[itsa svx]

Ok - checked and cleaned all of the connections under the hood with electronic spray and all are good but no changes. Swapped in another TCU an no difference at all. It's weird but it acts the same whether the TCU is connected or not - I can shift manually but it won't shift at all on its own. Still no check engine light and no codes stored - I know the light is good because it came on when I changed the TPS but cleared after I drove it a bit. Guess I will move on to checking the shift solenoids.

[89Laredo]

You can test the Solenoids through the plug, I have a picture floating around somewhere.
They should all be 14-16 ohms, IIRC.

I would pull the TCU plug off and measure the resistance from TCU ground to a good body ground, and check for power on the Yellow wire with the key on.

[may pop]

It is definitly the trans solenoids. Change them out and it will be good as new.
Ron

[itsa svx]

Yep - found both shift solenoids were bad but the lock up was good. Went ahead and changed all three out and now it is shifting good. Haven't had a chance for a far enough trip to see if it will still have the loss of power issue but think it was tranny fluid getting overheated that was causing it. I plan on taking it to a friends shop tomorrow that it didn't make it to without having to pull over a couple times last week.

[4.3LXJ]

Glad you got it fixed and that it wasn't serious.

[Mudderoy]

Yep - found both shift solenoids were bad but the lock up was good. Went ahead and changed all three out and now it is shifting good. Haven't had a chance for a far enough trip to see if it will still have the loss of power issue but think it was tranny fluid getting overheated that was causing it. I plan on taking it to a friends shop tomorrow that it didn't make it to without having to pull over a couple times last week.

Great news! Congrats!

[itsa svx]

Thanks everyone for the help on this. Just drive it about 65 miles and no problems. Thinks its good now.