Hello folks. New to the world of cherokee. I picked up a 1990 for the wife the other day(wanted out of the explorer) and it seems to have a farily common tranny issue. no automatic shifting at all. Shifts beautifuly if you do it manually. No slop no slip, just shifts fine. When I bought the jeep it came with another tranny to put in it. P.O figured the tranny was bad. Ahter finding this little goldmine of a site, I belive I should look outside the tranny. What I searched says to me shift cable adjustment, test and set TPS, replace TCU. Do I have this correct? Just wanted second opinion from someone that wasnt talkin out his Azz quite so much. Thanks.....
Chris

 

lucas additive made my tranny work it was acting similar lol

 

sounds like a tcu if it shifts fine manually.
I have one out of a 89 for 50 shipped...

Check fuses/grounds to tcu?

 

http://www.allpar.com/SUVs/jeep/cher...nsmission.html

Check that little thing out as well.
I adjusted mine and noticed a little improvement. Not a lot as an average driver wouldn't really notice the difference, but I do. Might also notice more because I drive a manual for my DD.

 

1. Verify TV cable adjustment

2. Test AND adjust your TPS. 87-90 TPS are adjustable and it is important.

Do nothing else before doing the above two things! Neither take a long time to perform.

Link on adjusting the cable.

http://naxja.org/forum/showthread.php?t=1015963


RENIX TPS
(Thanks to Joe Peters from NAXJA for this information)

MANUAL TRANSMISSION:

RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body. This manual transmission vehicle TPS provides data input to the ECU. The manual transmission TPS has three wires in the connector. Wire "A" is positive. Wire "D" is ground. Remove the three-wire connector from the TPS. Key ON, measure voltage from "A" positive to "D" ground. Note the voltage reading--this is your REFERENCE voltage. Now, reconnect the three-wire connector to the TPS. Key ON, back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. Adjust the TPS until you have achieved this percentage, if you can't achieve the correct output voltage replace the TPS and start over.

AUTOMATIC TRANSMISSION:

RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles--FOR ENGINE MANAGEMENT RELATED ISSUES. However, the automatic TPS also has a four-wire connector. For the automatic transmission equipped vehicles the four-wire connector provides data to the TCU. Disconnect the four-wire connector. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Now, reconnect the four-wire connector to the TPS. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. Adjust the TPS until you have achieved this percentage, if you can't replace the TPS and start over.

So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU. If you have TRANSMISSION issues check the four-wire connector side of the TPS. If you have ENGINE issues check the three-wire connector side of the TPS.

For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.

 

If the tranny does not shift out of first gear it's the TPS. No adjustment will fix that, it needs to be replaced.

 

This is true, just had this problem. But mine would not shift automatic or manually. I changed the TPS and now it shifts perfectly.

 

Mine just shifts through all the gears rapidly. I get to overdrive around 20mph no matter how I hit the gas peddle. I have changed the TCU with no luck. I have been driving it this way for 2 yrs. ????????

 

mine did this when i got it, you need to adjust your tv cable

the op check the fuse thats under the passenger side of the dash, if its blown the tranny will not work right

 

to test and see if the transmission is working properly you can take the little 10 amp red fuse out and shift manually. the red fuse is on the passenger side near the firewall directly above where your feet go. you will see it under there. this is for renix jeeps, my tps went bad in the 90 and ive been shifting manually till my new tps arrives.

 

thanks guys for all the quick responses. U guys are awsome. I figured i was headed in the right direction. This site is just full of info. im hoping to have the time to get to it later today, and ill check all recomendations listed above, starting with the fuse. Defiance, if it turns out to be the tcu, i'll let ya know. Thanks again.
Oh, and metlic53......i do drive fords.....3 of them....lol. Thats why the wife wanted a jeep.

 

Hello folks. Quick bump. Gave the kickdown cable a quick adjustment. And plan to jump on the TPS tomorrow with feet. I have read the info and links that many have posted and even understand how it is supposed to be done...lol. The one thing I seem to have missed is, of the four wires, which two go to the ecm, and which two go to the TCU?. I cant seem to find a schematic. anybody happen to have the colors off the top of there heads? Honistly, I havnt looked yet. I just want to be armed with as much knowledge as I can get. Thanks.

 

The TPS has two connectors with 3 wires each, a total of 6. The flat oval connector is for the ECU and the square connector is the one for the TCU.
The 3 wires on the square connector are:
pin A, red wire: +5 volt supply from the TCU (pin D1)
pin B, tan/orange wire: 1-5 volt output to the TCU (pin D2)
pin C, not used
pin D, grey wire: ground from the TCU (pin D3)

now, whatever you have read about the tps adjustment has nothing to do with the tranny operation, it has to do with the fuel injection finessing.
An unadjusted tps will slightly if not at all affect shifting, therefore adjusting it is absolutely useless to fix your problem.
A BAD tps though, can't be fixed and will keep the tranny stuck in 1st.

What you can do (and you won't find this in any manual or writeup on the internet) is to diagnose a bad tps output with a tester looking for "blank readings" between the 1-5 volt sweep. That means, you stick the tester + lead into the back of pin B and the other lead to ground (pin D if you want) and slowly, very slowly, rotate the throttle plate and watch the volt output increase on the tester display. If the tester randomly reads 0 volts, error, dots, blinks or whatever is not a number between 1 and 5 volts, the TPS IS BAD and needs to be replaced.

I told you all this for academic purposes only, since i beleive as i already said that just replacing the damn thing will save you time and energy.

 

Fantic, that was exactly what i was looking for. The tps on my mustang works exactly the same way, except it is only wired to send info to the ecu. and is adjusted in much the same way. Ill report back as soon as ive done the test on the tps, and checked the fuse to the tcu. Thanks'
Chris

 

The reason why the TPS is a dual model is because the renix ECU works with a decreasing output (5 to 1 volts) and the TCU with an increasing one. On the chrysler injections of 91-on both computers work with increasing values and the output wire is simply split in two at some point of the harness.