1990 Cherokee will not upshift (transmission? computer?electrical?) - JeepForum.com

 
LinkBack Thread Tools
post #1 of 6 Old 09-25-2007, 02:15 PM Thread Starter
davidtwyman
Registered User
2007 KJ Liberty 
 
Join Date: Dec 2004
Location: Pickerington
Posts: 30
1990 Cherokee will not upshift (transmission? computer?electrical?)

I drive a 1990 Jeep Cherokee, 4WD, 4.0L, automatic. It only has 80,000 miles on it but it drives weird. I have to get up to 35mph and 4200rpm for the Jeep to "upshift" into the next gear. Then, I have to go almost 65mph and 4200rpm to get the Jeep to upshift again. I have to begin the whole process over again if the Jeep falls below 25mph (after reaching 35mph) and 55mph (after reaching 65mph). As you can imagine, the run-out at 35 mph and 65 mph seems like the engine is going to blow and then it finally kicks in. It makes for a miserable drive and makes driving "work" versus pleasure. I have a lot of traffic in my commute also, which makes it even worse. Also, if I punch the pedal to the floor, there is no "downshift" that kicks the Jeep into a passing gear. It just gradually gets faster with no "passing gear". The Jeep runs at 3000+rpm when I am going 65mph and it should be around 2100 rpm. I had a Mercury Cougar that had the same exact problem and it was the fan clutch (doesn't sound right, but it was). I replaced the fan clutch hoping my problem would go away, but it did not. What is my problem? It sounds like an electrical problem as sometimes it will run like a normal Jeep for a week or two, then go back to the Jeep from Hell again. The Jeep is in great shape, but I need it to perform better....or else. I have changed the TPS, fan clutch, transmission fluid, and transmission filter. Could it be the computer or the transmission computer? I could really use some expert help to diagnose this problem before I take it in to a mechanic's shop to put it under a scope. I'm a do it yourselfer and would like to fix on my own before I give in to the shop.

davidtwyman is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old 09-25-2007, 02:37 PM
collkid
Registered User
2000 XJ Cherokee 
 
Join Date: Apr 2007
Location: Highlands Ranch, Colorado
Posts: 1,845
got that same issue and it wasn't my TPS either...

2000 Jeep Cherokee. 4.5', Long arms, Bumpers front and rear, Winch.
1992 Toyota Paseo DD 35+ MPG
Colorado Member #89
collkid is offline  
post #3 of 6 Old 09-25-2007, 03:04 PM
CharBroiled
Registered User
2000 XJ Cherokee 
 
Join Date: Aug 2007
Location: Northeast USA
Posts: 644
my 2000 looks like it has a mechanical downshift cable coming off the throttle body linkage.. at least the cable looks like it goes down to the tranny. maybe its broken or stuck? the tranny would think youre at wot all the time and have high shift points if thats what the cable is indeed for and its toast.

2000 Cherokee Sport 4.0L Selec Trac - mine - for occasional wheeling
2007 Patriot 2.4L FD I 4x4 - wifes - doomed to rarely leave the street
CharBroiled is offline  
post #4 of 6 Old 09-25-2007, 03:12 PM
jfiscus
Registered User
 
jfiscus's Avatar
1993 XJ Cherokee 
 
Join Date: May 2004
Location: middletown, ohio
Posts: 810
There is indeed a tranny kickdown cable connected to the throttle body, it is supposed to be "self adjusting" but the one on my old XJ was worn out & I had to apply a hose clamp to keep it in the correct position. Check that out first, cause it's pretty simple to fix.

There is also a TCU under your dash that might be shot? I think I have a couple of these in the garage if you're in need of one.

97 ZJ Limited, all power V8 AWD (wife's DD)
93 XJ Country 32" TSL Radials, 4.5" Rough Country Lift
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

91 XJ Laredo 33x15.5 TSL SXs, Homebrew 3" lift
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Local to Cincinnati, Ohio? Check out our club!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jfiscus is offline  
post #5 of 6 Old 10-01-2007, 01:15 PM Thread Starter
davidtwyman
Registered User
2007 KJ Liberty 
 
Join Date: Dec 2004
Location: Pickerington
Posts: 30
Can you identify the transmission kickdown cable next to the throttle body with a picture, please? I think I might see what you are talking about, but I do not see any way to adjust it.
If that doesn't work....I'll try anything....I'll try the TCU off of my father's 90 Cherokee to see if it works.
Did you ever get yours fixed? If so, what was the culprit?
davidtwyman is offline  
post #6 of 6 Old 11-20-2008, 05:10 PM Thread Starter
davidtwyman
Registered User
2007 KJ Liberty 
 
Join Date: Dec 2004
Location: Pickerington
Posts: 30
FIXED!!!!!
The problem was a bad TPS. The new one I put in was defective. I found this out when I purchased another one and it solved a problem I have had for several months.
davidtwyman is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
aw4 transmission dont 1-2 upshift when cold, fine when warmed up Blue70 XJ Cherokee Technical Forum 3 09-20-2009 02:48 PM
1990 XJ 4.0 Engine and accessories electrical failure while driving grimah1w XJ Cherokee Technical Forum 2 06-01-2009 04:14 PM
HELP !!!!! 1990 xj electrical problems cab101 XJ Cherokee Technical Forum 0 11-09-2008 02:40 PM
xj transmission computer sascuba XJ Cherokee Technical Forum 3 08-12-2008 05:09 PM
Starting Circuit Electrical Fault in 1990 Cherokee emhunde XJ Cherokee Technical Forum 2 05-20-2007 06:34 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome