The Throttle Position Sensor (TPS) is mounted to the side of the throttle body and connects to the throttle blade shaft. The TPS is a variable resistor that provides the PCM with an input signal (voltage). The signal represents throttle blade position. As the position of the throttle blade changes, the resistance of the TPS changes.
The PCM supplies about 5 volts of DC current to the TPS. The TPS output voltage (input signal to the PCM) represents throttle blade position. The TPS output voltage to the PCM varies from about 0.5 volt at idle to a maximum of 4.0 volts at wide open throttle. The PCM uses the TPS input, and other sensor input, to determine current engine operating conditions. The PCM also adjusts fuel injector pulse width and ignition timing based on these inputs.
In order to perform a complete test of the TPS and related circuits, you must use a DRB or equivalent scan tool, and follow the manufacturers directions. To check the Throttle Position Sensor (TPS) only, proceed with the following tests.
- Visually check the connector, making sure it is attached properly and that all of the terminals are straight, tight and free of corrosion.
- The TPS can be tested using a digital ohmmeter. The center terminal of the sensor supplies the output voltage. The outer terminal with the violet/white wire is the 5-volt supply terminal and the black/light blue wire is the sensor ground terminal.
- Connect the DVOM between the center terminal and sensor ground.
- With the ignition key to the ON position and the engine OFF, check the output voltage at the center terminal wire of the connector.
- Check the output voltage at idle and at Wide Open Throttle (WOT):
- For 1996 vehicles at idle, the TPS output voltage should be greater than 0.35 volt (0.4 volt for the 2.4L engine). At WOT, the output voltage should be less than 4.5 volts (3.8 volts for the 2.4L engine).
- For 1997 and later vehicles at idle, the TPS output voltage should be about 0.38-1.20 volts. At WOT, the output voltage should be about 3.1-4.4 volts.
- The output voltage should gradually increase as the throttle plate moves slowly from idle to WOT.
- If voltage measures outside these values, replace the TPS.
Before replacing the TPS, check for spread terminals and also inspect the PCM connections.