first off, my car in a 1990rs w/ 3.1L. i installed a new tps switch this summer and now ever sinceit gets a little cold in the mornings, when i first start the car, the rpm's fly up and my light comes on telling me to get it serviced. i drive the car for a few minutes, which sometimes can be rough with the car wanting to stumble, and after it runs for a little, the light goes off and it runs ok. i had problems with the three wire harness to the tps and i'm not sure if the switch is getting or giving off the correct signals. could this be the problem or is it something else. also, when i leave work, the car starts fine, but it still has that little stumble once and a while. also the light seems to come on, in the mornings when my car comes to an idle or off the gas.
any help with this would be greatly appreciated, due to the fact i can't afford the garage's rates. my 98 blazer already put me into the poor house with shop rates.
thanks,
bruce

 

The throttle position sensor is like a "volume" control (it's a potentiometer). It outputs from about 0.5 volts (at idle) to around 4.5 volts (at WOT) to the ECM. The black wire should be grounded, the gray wire should have 5 volts to it, relative to the black wire, and the dark blue wire is the output that varies with throttle position. Turn the ign on & chech the voltages with a meter. Also, the TPS may be adjustable - if it is, set it for an output of about 0.5 volts @ idle.

Tim

 

tim,
if the three wire harness going to the switch was bad, i take this could cause the problems i described eariler, with the engine fluctuating in rpm's ?
would this problem cause my car to start off with high rpm's in the cold morning's ?

thanks,
bruce

 

Yes, a bad wire in the harness to the TPS could cause that problem.