GM Cadillac Deville_Fleetwood_ELD_Seville 1990-1998

Throttle Position Sensor



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.

  1. Visually check the connector for cracks, or looseness, and that the connector is corrosion free.
  3. With the key ON, engine OFF, measure the voltage at Terminal B., the voltage should read about .5 volts.
  5. 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.
  7. Check terminal A for a proper ground signal.
  9. Check terminal C for a 5 volt reference signal. If the signals are correct, the sensor is faulty.
  11. If the signals are not correct, check the circuits for continuity.
  13. If the circuits are not faulty, the PCM may be at fault.


3.0L Engine
  1. Detach the sensor harness connector.
  3. Remove the 2 mounting screws.
  5. Remove the sensor from the throttle body

To install:

  1. With The throttle closed, hold the sensor in place against the throttle body.

Move the throttle gently by hand Ensure that the TP sensor is correctly seated on the throttle shaft.

  1. Install the 2 mounting screws, and connect the harness.

4.5 And 4.9L Engines
  1. Remove the air cleaner.
  3. Remove the TP sensor connector.
  5. Unscrew the 2 TP sensor attaching screws and retainers, and remove the TP sensor.

To install:

  1. With the throttle valve in the normal closed idle position, install the TP sensor on the throttle b