My '96 doesn't select 1st when put into D or 3. It does go into 1st when selecting 1-2, and will shift into 2nd at 4500rpm. Shifting manually from 1-2 to 3 below 4500rpm feels pretty solid, and it will shift to OD, so I think the trans is OK. The fluid isn't burnt and never has been.

I checked the TPS and was reading 5.1v input, .76v at idle and 3.7v at full throttle. The replacement registers exactly the same voltages.

The TCU has been swapped with a new unit, battery disconnected, terminals cleaned. The CEL is NOT on and its not showing any codes.

I've sprayed some carb cleaner around the engine compartment to see if there was a vacuum issue, but didn't detect any.

Added info: 156K miles, never offroaded, original owners. Trans has been serviced at least 4 times. It starts, idles and runs perfectly.

Help?

 

Good job checking the TPS. How is your kick down cable?
https://www.cherokeeforum.com/f2/free-quick-fix-41821/

 

I adjusted it several times with no change.

 

Bump!

 

Sorry, I have no other advice. I can guess the solenoids may be at fault but that's just a shot in the dark. I hope someone more knowledgeable will help you.

 

Update: I've since replaced the VSS with no change. Does anyone know of a procedure for testing the VSS? With the ignition on, what voltage should be present on which colored pin?

I'm also thinking that there may be a broken wire, most likely a bad ground wire somewhere. Does anyone have a diagram of the wiring to the TCU?

 

http://www.jeep4x4center.com/jeep-se....swf#toolbar=0

 

the link doesn't seem to work

 

I looked earlier today and it worked, sort of, the site/pages loaded slowly. I think if you had waited it would of loaded all ~500 pages.

 

try thishttp://www.jeep4x4center.com/knowled...ex.htm#service

 

sorry if it takes so long my pc is really really fast loading

 

It's a great resource thanks for posting it. BTW it loaded much faster the 2nd time I tried.

 

it was a different link page i think that why

 

much better, thanks!

 

I've been doing more research on the 'net and actually found what appears to be the Chrysler troubleshooting manual for the AW4. I can't remember where I found it, but saved the 3.1mb to my computer and printed it out besides. It has the pinouts of the connectors, instructions for using the DRB-II tester, and flow charts for troubleshooting.

The black 8 pin connector beside the dipstick is for the NSS. Also there is a 7 pin that connects the trans to the TCU. The row of 4 pins includes the 3 solenoids while the center pin in the row of 3 carries ground from the TCU to the trans. I checked the resistance of the solenoids with relationship to the ground post of my battery and while 2 show ~12.5 ohms, the other is showing what I'll call capacitance as its a high reistance 6K-19K ohms that counts backwards. This particular pin connects to the 1-2 shift solenoid.

After looking through the manual(s) again it appears that my reasoning was too focused on an electircal issue. While the symptoms also point towards other things, the fact that I can't electronically shift 1-2 or 3-2 has remained constant. Given this, I finally concluded that my 1-2 solenoid was in need of replacement. I don't have a good place to work, so was going to have a local trans shop drop the pan, change or clean the filter, and change the solenoid. Its much more easily done on a rack than lying flat on your back.....anyway, I called Aamco and an independent guy and asked for a price. The Aamco guy called back several hours later and quoted me $500 to change all (3) solenoids, change all of the fluid, and filter. He also told me they NEVER have had to change any AW4 solenoids.....smells like BS to me. The independent guy told me 1 to 1.5 hours labor @$70/hour plus parts and fluid and proceeded to tell me he never heard of such a reading on a solenoid, what a pain the dipstick tube is, and that the pan bolts might break....and that he had another in and ended up replacing the trans with a remanufactured for $3500.

I got an idea that the wire might be open in the pan and showing a high resistance short through the fluid, so decided to prove it. I put some trans fluid in a cup with a meter lead and one end of a 14ga wire, and then then put the other lead on the other end. It showd OPEN, as in no continuity, so disproved that theory.

I drank a beer and went out to the driveway. I jacked the passenger side up with a floor jack, put my jackstands under, and tested the 10mm bolts holding the pan. They were only snug, so I tried the bolt on the dipstick tube on the bellhousing. I couldn't get any leverage so found my 3/8" air impact and VOILA, it came loose. I drained the pan, pulled the pan bolts, and knocked the pan free with a deadblow hammer. The exhaust is IN THE WAY, so the pan can only be moved a little. Even so, the solenoids are visible.

I pulled the connector from the center solenoid and checked with the VOM. It gave me the same reading as when checking through the 7 pin connector, and with the lead off, the 7 pin showed "open" as it should have. The new solenoid is ordered, and I have 5 quarts of DexIII/Mercon waiting.