DirtDaddy

My son has a 90 XJ that got stuck in a deep puddle a couple of weeks ago (It has a snorkel BTW). Once we got it dried out and ready to drive again, We are having problems with upshifting (auto tranny) and random stalling. As I was troubleshooting the TPS, I found only about 0.2 volts on the output side. When I checked the input side, I was only getting about 1.1 volts. It's my understanding that I should be around 5 volts on the input side and 0.8 volts on the output side. Does anybody know where the 5v signal comes from? Is it the ECU? It's not out of the question that it got a little damp (the water was over the seats :-)

Anybody got any ideas where the problem could be?

andecase

IIRC the TPS should only be at 5 at WOT. so if you didn't do that check that.

also check your tranny fluid for contamination.

Torkrench

I just dealt with this first hand on a friend's jeep the other day! First thing I thought was ECU problem or damaged wire. Checked the voltage at the ECU with a power probe and found it was outputting the 5v it was supposed to(actually closer to 7v at the ECU pin). Went up front, disconnected the sensor and found the 5v was there with the sensor unplugged.

Turns out the sensor had shorted out internally and would drop the input voltage when plugged in. Replaced the TPS and all was fine. This was on a Renix, not sure what year yours is, but I bet it is the same problem.

DirtDaddy

Torkwrench...You called it. Unplugged the TPS and the bus voltage jumped right up to +5vdc where it should be. Replaced it, calibrated it and we're good to go!
Thanks for the help!

Torkrench

It's funny that you had that problem so soon after I saw the same issue. I had searched and hadn't seen anyone else post with the same symptoms. At least it's a quick fix.