The Throttle Position (TP) Sensor is a potentiometer that provides a voltage signal that changes relative to the throttle blade angle. It is connected to the throttle shaft on the throttle body. By monitoring the voltage on the signal line, the PCM calculates throttle position. As the throttle blade angle is changed (accelerator pedal moved), the TP sensor signal also changes. At a closed throttle position, the output of the TP sensor is low. As the throttle blade opens the TP sensor voltage increases so that at Wide-Open Throttle (WOT), The TP sensor voltage should be above 4 volts. The PCM calculates fuel delivery based on throttle blade angle (driver demand).
A broken or loose TP sensor may cause intermittent bursts of fuel from and injector and unstable idle because the PCM thinks the throttle is moving. A hard failure in the TP sensor 5 volts reference or signal circuits should set a DTC. A hard fault in the ground circuit will also set a DTC. Once a DTC is set, the PCM will use an artificial flow for throttle position and some vehicle performance will return. A high idle may result when there is a hard fault in the system.
- Visually check the connector for cracks, or looseness, and that the connector is corrosion free.
- With the key ON, engine OFF, measure the voltage at Terminal B., the voltage should read about .5 volts.
- Operate the throttle smoothly to wide-open throttle (WOT), the voltage reading should follow the lever action, but not exceed 5 volts. If it does, or the voltage reading jumps, then replace the sensor.
- Check terminal A for a proper ground signal.
- Check terminal C for a 5 volt reference signal. If the signals are correct, the sensor is faulty.
- If the signals are not correct, check the circuits for continuity.
- If the circuits are not faulty, the PCM may be at fault.
REMOVAL & INSTALLATION
- Detach the sensor harness connector.
- Remove the 2 mounting screws.
- Remove the sensor from the throttle body
- With The throttle closed, hold the sensor in place against the throttle body.
- Install the 2 mounting screws, and connect the harness.
- Remove the air cleaner.
- Remove the TP sensor connector.
- Unscrew the 2 TP sensor attaching screws and retainers, and remove the TP sensor.
- With the throttle valve in the normal closed idle position, install the TP sensor on the throttle body assembly.
- Install 2 TP sensor attaching screws with retainers. Do not tighten the screw until the TP sensor is adjusted.
- Install the TP Sensor connector. Adjust the TP Sensor and perform the idle learn procedure.
To Perform the TP sensor adjustment.
- Disable the generator by grounding the green harness connector plug adjacent to the generator.
- Start the engine, enter diagnostics, and select PCM override PS103 'ISC Actuator'
- Press the 'COOLER' button on the CCP to retract the ISC Actuator. This action will disengage the A/C compressor and command the EGR 'OFF'. The Climate control center display will change from '50 to 00'. The ISC Actuator will slowly retract (about 20 seconds) to a fully retracted position. Verify that the throttle lever is resting on the minimum idle speed screw. With the ISC Actuator plunger fully retracted, disconnect the ISC harness.
- Select the PCM data PD01, 'TP Sensor', while still in PCM override PS03. Note the throttle position (in degrees) displayed on PCM parameter PD01.
(-0.5° TO + 0.5°)
No TP sensor adjustment required. Reattach the ISC Actuator harness and disconnect the grounding wire at the generator.
- TP Sensor (-10.0° TO -0.6°) or TP Sensor (+ 0.6° TO + 90.0°) TP Sensor adjustment required.
With the engine 'OFF' and the ignition 'ON', reenter diagnostics and select PCM override PS03 'ISC Actuator'. Press the 'COOLER' button to retract the ISC Actuator the minimum air setting.
- Loosen the TP sensor screws just enough to permit the sensor to be rotated. Open the throttle slightly and allow the throttle lever to snap shut against the minimum air screw. Adjust the TP sensor so the parameter display is 0°. Tighten the TP sensor mounting screws with the sensor in the adjusted position. Recheck the parameter to be sure the TP sensor parameter is (-0.5° to + 0.5).
- Install the air cleaner.
- Disconnect the negative battery cable.
- Remove the throttle body assembly.
- Remove the TP sensor electrical connector from the TP sensor.
- Remove the TP sensor mounting bolts from the TP sensor.
- Remove the TP sensor from the throttle body.
- Discard the O-ring.
- Install the new O-ring onto the TP sensor.
Install the TP sensor onto the throttle body.
- Tighten the TP sensor screws to 20 inch lbs. (2.3 Nm).
- Install the TP sensor electrical connector to the sensor.
- Install the throttle body assembly.
- Connect the negative battery cable.