I have been in arrears in performing diagnostic work on my Xj. A new IAC has helped reduce my engine start rpm flare and I found the TPS output signal (i.e., terminal C in the connector) to only provide a millivolt level signal yet, this is supposed to be a volts level signal.
Renix vintage Xj control systems desire the TPS output to be 83% of the input/supply voltage. Note I converted my '88 Xy from the auto to an AX15 years ago and installed the correct PCM for a manual transmission. I also learned here at that I could still use the auto TPS. Hopefully, this remains correct. I should also add that I have tested (2) used auto TPS sensors and (1) used manual TPS sensor in addition to the new auto TPS sensor I just purchased today.
Here is a (potentially) useful summary and recall the TPS is a simple potentiometer:
Measurements A-B: TPS input; A = B+/Start signal, B=Ground, shared with coolant Temp., Air Temp and MAP. If MAP was messed up I think this would result in a no start. In turn, I suspect my TPS ground is okay. When I measure A - to engine ground I still obtain a good supply voltage signal yet, it is slightly higher than that measured at "A."
B-C: TPS output and the "C" measurement is the obvious problem.
Lastly, note I have used the manual TPS to check voltage at "A" and "C" while exercising the wiper arm of the sensor and the voltage output did vary with wiper motion.
Going out now to repeat some measurements on the new auto TPS.
Renix vintage Xj control systems desire the TPS output to be 83% of the input/supply voltage. Note I converted my '88 Xy from the auto to an AX15 years ago and installed the correct PCM for a manual transmission. I also learned here at that I could still use the auto TPS. Hopefully, this remains correct. I should also add that I have tested (2) used auto TPS sensors and (1) used manual TPS sensor in addition to the new auto TPS sensor I just purchased today.
Here is a (potentially) useful summary and recall the TPS is a simple potentiometer:
Measurements A-B: TPS input; A = B+/Start signal, B=Ground, shared with coolant Temp., Air Temp and MAP. If MAP was messed up I think this would result in a no start. In turn, I suspect my TPS ground is okay. When I measure A - to engine ground I still obtain a good supply voltage signal yet, it is slightly higher than that measured at "A."
B-C: TPS output and the "C" measurement is the obvious problem.
Lastly, note I have used the manual TPS to check voltage at "A" and "C" while exercising the wiper arm of the sensor and the voltage output did vary with wiper motion.
Going out now to repeat some measurements on the new auto TPS.