kumearl

trannny shifts fine when cold then has problems upshifting and sometimes semms to go into neutral. changed tranny because of problem .this tranny came out of my other cherokee ,never had trouble with it in four years now it acts like the one I yanked , and I'm thinking I didn't need to switch them. any help is welcomed

AutomaticKrackr

More information on your xj would be Helpfull. IE..year..2 or 4X4.The type of transmission would be helpfull.....Anyway I have nothing but goodluck with lucas transmission treatment.Do a trans flush with 1 quart of the lucas.The rest with the recommended trans fluid.

kumearl

90 4.0 auto japanese trans.4x4 trans has over 200k out of my old xj no trouble with it before thinking it is something electric

tjwalker

Test your "throttle position sensor"

It is directly involved with transmission shifting characteristics and it is a relatively common failure!

Also be sure that your TPS is adjusted properly. Adjustment is required on 87-90 AW4. Even if you install a new one, it must be adjusted.

More on this.

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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.