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  #1  
Old August 14th, 2010, 09:08
CAMO XJ CAMO XJ is offline
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94 XJ will not shift itself

1. Year of your XJ/MJ.
1994 jeep cherokee xj sport
2. Engine (I.E.: 4.0, 2.5, 2.8).
4.0 inline 6
3. Transmission (Manual or auto).
auto and I make the assumption its an aw4
4. Differential/transfer case.
dana 30/35 with a np231
5. Any other model year specific info that would apply to your tech question.
Ok Here is the problem. The Jeep has 205k and the trans has shifted fine until today. I had a guy coming to buy it so I went outside to drive it to the store one last time and.........

I put it in drive which is how I drive it around town so it wont shift to od and lug with the stock gearing, and it wont pull. You could give it gas and feel that it was trying to move but wouldnt. I then pulled it down into what the shifter says as 2 and it takes off fine. You can then shift it up through all the gears fine. However when giving it gas to use a passing gear it will not gear itself down. When you come to a stop you have to downshift it and take off. Its almost like a manual valvebody in a c4 or something. Any ideas what the problem is? I adjusted the cable on the tb hoping that would help and nothing.
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  #2  
Old August 14th, 2010, 09:15
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Tim_MN Tim_MN is offline
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Re: 94 XJ will not shift itself

The Throttle Position Sensor would be the first suspect. Test it. If testing is beyond your skills, simply replace the TPS with a quality replacement from O'Reilly or NAPA. Advance and IdiotZone sell cheap crappy parts.


Physical Symptoms:

The engine loses power and might be stalling. The engine will idle, but might die as soon as you press the gas pedal. When driving, it may seem as if all power is gone. Sometimes speed maxes out around 25 mph, and it feels as if the transmission is failed or isn't shifting properly, if at all. You might be going 25mph down the road at 5,000 RPM's. If you quickly jump on the gas you might be able to get the transmission to shift into second, but it won’t shift properly by itself. Shifting manually, the transmission goes through all the gears.

TEST

You should have 5 volts going into the TPS. At idle, TPS output voltage must be greater than 200 millivolts. At wide open throttle (WOT), TPS output voltage must be less than 4.8 volts.. The best is to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. One of the other wires should show .26V (or so). The other wire will be the ground and should show no voltage. Move the throttle and look for smooth meter response up to the 4.49 at WOT.
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Last edited by Tim_MN; August 14th, 2010 at 09:19.
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  #3  
Old August 14th, 2010, 09:24
CAMO XJ CAMO XJ is offline
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Re: 94 XJ will not shift itself

I have a digital voltmeter but not an analog... Will it work or no?

And the engine makes good power and runs strong. I feel no difference in the engine performance or idle or anything like that.

YOu just have to manually shift it to take off or pass a car.


This is why I wondered if it was the tps.

Last edited by CAMO XJ; August 14th, 2010 at 09:29.
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  #4  
Old August 14th, 2010, 10:04
CAMO XJ CAMO XJ is offline
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Re: 94 XJ will not shift itself

anymore ideas???
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  #5  
Old August 14th, 2010, 13:16
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Johnnie Walker Johnnie Walker is offline
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Re: 94 XJ will not shift itself

Check fuse for the TCU (under pass side dash), and then unplug the TCU and shift manually and see if that works. TCU may be the problem if the TPS is not.
If all else fails, buy a new TPS and see if that solves the problem?
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Old August 14th, 2010, 13:25
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Re: 94 XJ will not shift itself

Quote:
Originally Posted by CAMO XJ View Post
I have a digital voltmeter but not an analog... Will it work or no?
.
Yes
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  #7  
Old August 14th, 2010, 13:30
CAMO XJ CAMO XJ is offline
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Re: 94 XJ will not shift itself

Quote:
Originally Posted by Johnnie Walker View Post
Check fuse for the TCU (under pass side dash), and then unplug the TCU and shift manually and see if that works. TCU may be the problem if the TPS is not.
If all else fails, buy a new TPS and see if that solves the problem?
I can shift it manually now. It just won't shift itself.
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Old August 14th, 2010, 15:04
joe_peters joe_peters is offline
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Re: 94 XJ will not shift itself

Test your solenoids and harness: http://www.transonline.com/transdige...ers/index.html

There are four pages to the article.
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Old August 14th, 2010, 17:18
CAMO XJ CAMO XJ is offline
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Re: 94 XJ will not shift itself

I will try that tmw.
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  #10  
Old August 14th, 2010, 17:22
CAMO XJ CAMO XJ is offline
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Re: 94 XJ will not shift itself

And after driving it more here is how it does on the shifter I have a 2, a D, and OD. When you put the shifter in OD the Jeep does not want to mover at all.
When you put it in D it trys a little harder
And when you pull it to 2 it is like normal and should be.


So you take off in 2 and shift to D and you can feel it shift to second and then drive real fast.

Then if you try to hammer it while going it will not gear itself down.
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Old August 14th, 2010, 17:45
CAMO XJ CAMO XJ is offline
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Re: 94 XJ will not shift itself

BTw I checked the tps voltage and it only goes to like 3.8 at wot
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  #12  
Old August 14th, 2010, 18:09
lawsoncl lawsoncl is offline
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Re: 94 XJ will not shift itself

Quote:
Originally Posted by CAMO XJ View Post
And after driving it more here is how it does on the shifter I have a 2, a D, and OD. When you put the shifter in OD the Jeep does not want to mover at all.
When you put it in D it trys a little harder
And when you pull it to 2 it is like normal and should be.


So you take off in 2 and shift to D and you can feel it shift to second and then drive real fast.

Then if you try to hammer it while going it will not gear itself down.

With the shifter in (D), if its trying to start in 4th gear then the problem is usually power to the trans computer (often just the fuse) or the trans computer itself is bad (fairly rare). The link above http://www.transonline.com/transdige...ers/index.html is a good place to start - in particular verifying you have power to the trans computer.
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Old August 14th, 2010, 18:19
CAMO XJ CAMO XJ is offline
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Re: 94 XJ will not shift itself

To me it seems like if it's on OD it trys to start in 4th and in D it trys to start in 3 and then when pulled to 2 it starts in first and shifts to 2 and 3 when shifted to D from 2.
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  #14  
Old August 15th, 2010, 08:56
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Tim_MN Tim_MN is offline
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Re: 94 XJ will not shift itself

Dude, buy a $30 TPS and be done with it. If you don't need a TPS now, you will need one later.
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  #15  
Old August 15th, 2010, 09:21
Shorty Shorty is offline
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Re: 94 XJ will not shift itself

Quote:
Originally Posted by CAMO XJ View Post
To me it seems like if it's on OD it trys to start in 4th and in D it trys to start in 3 and then when pulled to 2 it starts in first and shifts to 2 and 3 when shifted to D from 2.
it probably seems that way because that's what it will do without power to the TCU-- I think Lawsoncl covered it, but check for power to the TCU before you spend anything. If it's not getting power, start working backwards from the TCU plug to the fuse box. You'll find an inline fuse for the TCU before you get to the fuse box.
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