GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Throttle Position (TP) Sensor



The TP sensor wiring should consist of a 3 wire harness connector. The gray wire is normally the 5 volt reference signal from the computer control module. The dark blue wire should be the TP signal and the black wire is ground.

Because the TP sensor on these engines is bolted into a fixed position, no adjustment is necessary or possible. If the sensor does not give proper readings (and other problems with the circuit are not to blame), the faulty TP sensor must be replaced.

  1. If available, connect a scan tool to the ALDL/DLC. If a scan tool is not available, use a digital voltmeter to backprobe the TP sensor connector terminals for the ground (black wire on end of connector) and sensor signal (dark blue wire usually at center of connector). By backprobing the connector a voltage reading can be taken without disconnecting the circuit and without piercing the wires.
  3. Turn the ignition ON , but do not start the engine. Check the voltmeter or scan tool for TP sensor output. Voltage should be 1.25 volts or less with the throttle closed. Open the throttle and watch for a smooth change as the voltage increases. Voltage may go as high as 4.5 volts at wide open throttle. If voltage with the throttle closed is greater than 1.25 volts, or if the voltage does not increase smoothly as the throttle is opened, replace the sensor.


The throttle position sensor is an electrical component. Do NOT soak it or clean it with solvent or the sensor could be damaged.

For sensor removal and installation, please refer to electronic engine control information in Chapter 4 of this manual.