ABout two months ago i had trany problems so i replaced it didnt fix it.
i changed the speed sensor, didnt fix it.
i tried eveything and finally found i thread on here that said it could be the TCU, and so what i did was disconected it from the system, and it fixxed my problem been driving ever sence just had to shift it manualy and didnt have 2nd gear, well bout a new TCU and still got the same problem when its plugged in, im figuring its got to be wiering to the TCU, but where do the wiers go? what are the conected to? any ideas?

 

a repair manual will be needed for you to follow the wires

 

PM Sent

 

What sensor did you replace?

Did you replace the "throttle position sensor" on the throttle body? If not, that sensor is absolutely suspect here as it is directly involved with transmission shifting characteristics.

 

i drive it fine, i took out the transmission contoll unit and i can shift it fine, just have to do it manually, so i know for a fact that its got to be the wiering to the tcu because when i unpluged it it runs fine just have to shift it manualy and when i plug it in it feels like the tranny is slipping at first then it get wors and eventally will not shift out of first gear. whats happening is it thinks it needs to down shift but it catches its self that why it feels like it slipping, and then eventaully it wont shift at all and its stuck in first no matter what i do it wont come out of first but it dose go in revers and park just wont shift above first gear. i thought it could be the TPS for a while but when i unplugged the TCU it kinda ruled out the TPS

 

did you clean the connectors to the tcu and where did you buy it

 

didnt even thing about it, what should i clean it with? i bout the new one from george the jeep didnt work so i went back and they gave me my money back 10 bucks cant really go wrong haha
they said to try and clean the conectores under the hood too i still have to try that

 

Nope. The throttle position sensor is still in play here.

Unplugging the TCU completely removes the "electrical" component of the transmission, but it does NOT rule out a faulty TPS.

You must test that TPS. Failure to do so could result in chasing your tail. A failing TPS is very common on your vintage XJ. And along with testing, you must verify the "adjustment", as that is very important. Your 89 has an adjustable TPS. Here is more.


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.

 

under the hood the tcu is in side the cab have you checked the fuse to the tcu ? electrial contact cleaner, tooth brush

 

tcu fuse no 13?

 

I couldn't agree more with tj.... Change out the TPS and I can say with some confdence that it will probably solve the shifting issue (especially since I just had the same exact problem). If, however, it doesn't solve the issue, you will only be out of about $42 and you'll be able to scratch it off the possibilities.

BTW, another symptom you may get is stalling after revving to about 3 grand and letting completely off the throttle (in nuetral). The TPS can also have an effect on your RPM regularity.

 

no the conectores under the hood theres like two ones black and if that ones not fully conected it wont start and the other one is gray and it would cause tranny problems under the hood. i know where the tcu id how els would i have put a new one in???

 

actually i have had the stalling problem sometimes, but i figured it would just have been the teriable oil presure i have. i have a new oil pump im putting in cause my car heats up to normal temp then the oil presure drops and the motor rattles a little, could all this be linked to the TPS?
still bouts to change the oil pump cause i have it and pan gasket needs changing anyway.

 

where do i find the TPS?

 

It was the TPS i tested it with a meater the out put was almost nothing, it was fried haha.
Put a new one in and it works great!