How To Calibrate The 1988-1992 TPS
Vehicles equipped with a throttle position sensors for year models 1988 through 1992 have an adjustable sensor that has to be calibrated (if replaced with a new one).
This type of TPS is located under the throttle body and the throttle body usually has to be removed to gain access to it, therefore, the TPS adjustment has to be done before you re-install the throttle body:
This is what you'll need to do:
Install the new TP sensor and connect it to its electrical connector -but do not tighten the two screws.
Place you multimeter in Volts DC Mode and turn the key On (if you disconnected the battery negative terminal to take the throttle body and sensor off, you'll need to reconnect the battery).
With the red multimeter lead probe the signal wire of the TPS (this is the middle wire in the connector). Connect the black multimeter to ground.
With the throttle plate closed, adjust the TP sensor till your multimeter reads between 0.38 and 0.42 Volts DC.
Once there, tighten the two TP sensor screws. The sensor is now calibrated.
Re-install the throttle body.
Use a new gasket on the throttle body. Also, don't use any type of gasket sealer or sealant (RTV Silicone) on the Gasket since this will later create a vacuum leak.
Before starting the vehicle, disconnect the battery for at least one full minute.
This will reset the closed throttle value, inside the PCM, back to 0.
And you're done!
Where To Buy The TPS And Save
The following links will help you comparison shop for the throttle position sensor:
Not sure if the above TPS fits your particular 3.8L V6 GM vehicle? Don't worry. Once you get to the site they'll ask you for your vehicle's info. If it doesn't fit, they'll find you the right one.
If this info really saved the day, buy me a beer!