P0750 on a stock LX450 - Shift Solonoid? (1 Viewer)

[yoda-g3]

My wife's '97 LX450 with about 155k on it threw a P0750 code a couple weeks back during a bad plug wire fiasco, I cleared it and put a new Ultraguage on and while driving home at 60-65mph in 95 degree weather while pulling a 2,000lb trailer the Ultraguage start barking at me that a pending code has been detected. No CEL, and the rig was driving fine, temp never bumped over 225, and that was very brief on a decent grade.

This rig has about 500 miles of light towing on it in its life and after my fiasco with the blown tranny on my now sold '02 LX I'm a little worried. 80's are usually pretty solid tranny wise so could this be something else up the line? Search only yield once vague reference that maybe a speed sensor or cam sensor could be part of it?

I was also towing with OD on since it was such a light load if that could've bene part of it. Just weird that the CEL on the dash didn't light up either time.

 

[TrickyT]

Interesting. I didn't know our ECUs would report a diagnostic trouble code without MIL being set. Maybe since it's not an emissions-related DTC the same code has to be triggered on multiple trips before the MIL will light. And if you do multiple trips without the code being re-triggered the DTC may clear on its own.

When's the last time you changed your ATF? Maybe a partially-clogged filter? P0750 is "Shift Solenoid "A" Malfunction: Trouble Areas: shift solenoid valve #1 is stuck or closed; valve body is blocked up or stuck." Sounds to me like the ECU detected this condition once, perhaps while on the steep hill, but then not again. I'd clear the DTC and continue to monitor.