TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > Transmission & Drivetrain > Eagle and Jeep Specific drive-train issues
  New Posts New Posts RSS Feed - AW-4 Is Shiftless...Except Manually
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

AW-4 Is Shiftless...Except Manually

 Post Reply Post Reply Page  12>
Author
Message
Buzzman72 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Sep/15/2009
Location: Southern IN
Status: Offline
Points: 2713
Post Options Post Options   Thanks (0) Thanks(0)   Quote Buzzman72 Quote  Post ReplyReply Direct Link To This Post Topic: AW-4 Is Shiftless...Except Manually
    Posted: Nov/05/2013 at 10:20am
A family member has a high-mileage '87 Comanche pickup with the AW-4.  For some time now, the transmission has refused to automatically upshift.  yet if you manually select the gears, every gear seems to work.

So...25+ years in...could it be that the control module is bad?  How would I test it?  Or is there some other reason the tranny won't automatically shift.  When this person bought the truck, it shifted perfectly...then suddenly stopped shifting on its own.

My son is considering buying the truck, if the problem isn't something that'll cost an arm and a leg to repair.  So any advice will be appreciated.  I'm just the man in the middle here, and I don't want to steer anyone the wrong way.
Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects.
Back to Top
whizkidder View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum


Joined: Mar/03/2008
Location: North Georgia
Status: Offline
Points: 2972
Post Options Post Options   Thanks (0) Thanks(0)   Quote whizkidder Quote  Post ReplyReply Direct Link To This Post Posted: Nov/05/2013 at 10:36am
Farna will know more, but seems strange. IIRC, the AW4 uses three shift solenoids -- one for the lockup converter, and two to control 1-4.

Sel 1 by itself is 1st, Sel 1&2 together is 2nd, Sel 2 by itself is 3rd, and both off = 4th (OD).

The shift lever does give you some control over the shifting, but IIRC, it isn't 1-2-3-4 like you'd expect, but that may depend on the version of the valve body on the tranny.

Your problem could be as simple as a loose/broken connection between the computer and the solenoids in the tranny -- particularly the ground.

I modified a 2001 Toyota Tacoma with an AW4 to shift manually by splicing toggle switches into the wiring harness between the computer and tranny -- allowed me to lock the converter at will, and select whatever gear I wanted. Farna has a similar setup in his wagon.

Edited by whizkidder - Nov/05/2013 at 10:39am
Ron Frost
marne1ancient @ gmail.com
910 nine two two 0563

"There is no limit to what a man can do, so long as he does not care a straw who gets credit for it. Charles Montague
Back to Top
carnuck View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Mar/31/2010
Location: Seattle
Status: Offline
Points: 3942
Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: Nov/05/2013 at 7:02pm


The fuse holder likes to corrode by the controller box. If the power/comfort switch doesn't light up, it's not getting power from either the inline fuse or the one in the fusebox.
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19611
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Apr/10/2014 at 10:29am
Check the fuse and fuseholder first, but most likely the controller has gone out. You can get replacements, but they are a bit on the high side (around $300? Was $270 or so when I checked... heck, that was 10 years ago!).

The easy way to heck the solenoids is with toggle switches. Using a wiring diagram for the TCU connector, find the three wires that go to the solenoids. One is lock-up, two are for shifting. You can leave the lock-up alone for now, or wire it to power (on all the time). The trans won't lock the converter when in first gear no matter what. Just remember to switch to first before stopping or engine will stall (just like not pushing in the clutch on a stick shift).

For the two shift solenoids, wire power to two toggle switches, then the other side to the solenoids. I just tin the ends of wire with solder and push in the TCU connector. Both switches on is first gear, both off is fourth (OD). 2nd and 3rd are one on one off... don't recall which is which though. Easy enough to find out! With this setup you can manually shift gears with the lever in "D" (or "OD"). It's easy enough -- start with both on, flip the 2nd gear toggle off (hmmm... which one?). Third gear is a little tricky as one has to be flipped off while the other is flipped on, but 4th is easy again.

You can see that's not a convenient arrangement because of the 2-3 up and down shift. I wired a four position rotary switch so I an "dial" the gears up and down. Only takes a couple diodes to do this.

If I do another I'll wire for five "speeds" though. The AW4 engine brakes in the top two gears (3-4 in "OD", 2-3 in "D"). When shifting with the lock-up on all the time (my normal shifting -- been doing it for 11 years now!) there is a definite "jerk" on the 2-3 shift unless you take your foot off the gas. This is the sprag (one-way) clutch kicking in. What I'll do next time is leave the lock-up toggle out and wire it so that there is no lock-up in 1-2-3. "4th" will be 3 + lock-up, then "5th" will be OD + lock-up. That will make shifting smoother and shouldn't affect performance... unless it improves it.
Frank Swygert
Back to Top
carnuck View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Mar/31/2010
Location: Seattle
Status: Offline
Points: 3942
Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: Apr/12/2014 at 9:51am
Man, I've been selling those controllers waay too cheap! LOL! $50 apiece used.I even have one from a '93 Grand Cherokee
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19611
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Apr/12/2014 at 6:48pm
I have another used one but haven't tried it yet. I installed a used one years ago and it lasted two weeks. If you could guarantee a used one to last it would be worth a lot more, but as it is $50 is a fair price, IMHO.
Frank Swygert
Back to Top
carnuck View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Mar/31/2010
Location: Seattle
Status: Offline
Points: 3942
Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: Apr/13/2014 at 11:09am
Yours was toasted from a short in the harness though IIRC? 
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19611
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Apr/14/2014 at 7:36am
I never found any shorts or anything wrong at all. Ohmed out every wire! If I'd have found something I'd have fixed it and got another used one, or bought a remaned unit. The only thing I could figure was possibly a voltage spike from the alternator. I did have to replace it about a year later. I just decided I liked the manual switch shifter good enough to keep and improve it. 
Frank Swygert
Back to Top
gui67 View Drop Down
AMC Apprentice
AMC Apprentice


Joined: Nov/11/2013
Location: France
Status: Offline
Points: 45
Post Options Post Options   Thanks (0) Thanks(0)   Quote gui67 Quote  Post ReplyReply Direct Link To This Post Posted: May/01/2014 at 10:53am
HEllo,
I have the same problem in my fathers Pacer with the AW4 swap:
the trnasmission was OK on the Cherokee.
Now, it is working OK, for 15 to 20 minutes, and after some time, it downshifts to first and will not run.
When I remove the fuse of the TCU, the transmission shifts manually without any problem.
If I stop the car and let it cool, it will work again in automatic mode for some moment.
So I think it is not related to the transmission, but more to the electronics.
Is there a way to check the cause of the problem? Do you have an idea?

the TCU is from a early AW4 and the transmission is a late model. I had to change the connectors to connect the transmission to the harness. the VSS sensor is also not the same (4 pulse per rev instead of the reed switch with one pulse per rev.)
Back to Top
carnuck View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Mar/31/2010
Location: Seattle
Status: Offline
Points: 3942
Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: May/01/2014 at 1:17pm
Is the trans from an HO ('91 up)? If so, and you converted the VSS, then I think you need a '91 Wrangler VSS to get the single pulse per rev. That's what I bought to put the HO efi in my '84 J10. It has a speedo cable connector and an EFI pulse sensor.
Back to Top
 Post Reply Post Reply Page  12>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.188 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or