Been fighting this for a while so i don't recall if i got a code or not that caused me to find it. but its been idling rough, off and on, surging, shifting funky as expected, A/C compressor not working consistently, and a few other issues. Some investigation online shows others have had this issue...4.5 volts at the SIGNAL wire, with it unplugged from the TPS and key on. So obviously the signal wire is shorted to a voltage source somewhere. the connector to the TPS was cracked and causing all kind off issues but that has now been replaced. Traced wires back to behind the block where they run into the large main harness and none are stuck together. no voltage seen prom the corresponding PIN on the PCM with power on, so i don't think its coming from there. now the fun part? my test light works fine...if there's voltage there it lights up but not on the TPS connector. But i can however find voltage with the voltmeter. one of the weird things is ALLDATA is showing a chart asking if its getting MORE than 10 volts on the signal wire.....seems like a hell of a lot of voltage since 4.5 volts is already enough to signal wide open throttle.
Tech at one of the dealers said to check all other sensors since some times they can cause the issue as well. So far haven't found anything on MAP sensor or trans control module, but haven't checked A/C pressure switch yet. i am not looking forward to having to sort thru all those wires in the harness, so I'm looking to find out if anyone else knows a known culprit that causes this more often than others, so i can possibly cut the trouble shooting time down.