[blue chevy man]

Hi Guys,

I have a '92 chevy 1/2 ton 2wd w/350 and auto.

For a couple years now I've been fighting an issue with a high idle and an occasional code 21, tps voltage high. I'm not new to these systems but am stumped at this point. The problem was intermittent and is now occurring more often so I'm forced to fix it. Most of the time the truck will just idle high and throw no code. It idles so high it will spin the rear tires on ice when stopped. I have installed two tps that I got from a local parts store. I suppose it's possible I got a bad batch but I don't know. I have a good 5v reference signal to the sensor but the sensor reads 5.0 v at idle and .8v at WOT. That's backwards. I am going to replace the sensor tomorrow because I did notice a dead spot in the sensor when moving it from idle to WOT but I can't figure out why the reading are opposite what they should be. The tps can basically only go on the tbi one way and I've replaced many of them on other trucks in the past with no issues.

Also, could I have a bad computer? I have checked the ECM ground, tps gray and dark blue wires to the ECM, MAP wires to the ECM and they are all good.

Any thoughts would be appreciated.

Thanks,
Jason