The TP (Throttle Position) sensor is a potentiometer providing the PCM with a signal directly proportional to the position of the throttle plate. The TP sensor is mounted on the side of the throttle body and is connected to the throttle plate shaft. The throttle position sensor or TPS's task is to monitor the amount the throttle plate moves. Moreover, it is also responsible for monitoring the throttle plate's position. However, the TPS transmits an electrical signal to the PCM. Of course, the powertrain control module uses the TPS signals to calculate EGR operation, Spark Timing, air/fuel mixture, and much more. Most importantly, all this is done based on engine load and various throttle positions. TP sensor gets specified 5 volts reference and ground circuit from PCM. There is also a return signal circuit. This circuit is connected to a wiper that moves along resistor inside the sensor. At wide open throttle, the wiper creates a loop between reference signal and reference return signal. This sends nearly full 5 volt signal back to the PCM. At Idle, return signal should be about 0.9 volts. To test the sensor with the engine not running and the ignition on check the voltage at the signal return circuit with a DVOM. The voltage must be between 0.2 and 1.4 at idle. Now move the throttle pulley to the Wide Open Throttle position. The voltage should rise to just under 4.8 volts. If there is no voltage, check the wiring harness for supply voltage and ground; if both are present but there is no output voltage from the TP sensor, it should be replaced, otherwise, the necessary repairs should be made if supply voltage and ground are not to specifications. To remove the sensor, you must detach the negative battery cable and wiring harness from the TP sensor, and then take off the two mounting screws. Once this is done, you can pull the sensor from the throttle shaft. To install the sensor, slide the rotary tangs on the sensor over the throttle shaft and rotate the sensor clockwise to the installed position. Take care not to damage the sensor or allow the engine to idle at a high speed. Install the mounting screws and tighten them. Reconnect the wiring harness and reconnect the negative battery cable.