The Throttle Position (TP) sensor is a potentiometer that provides a signal to the PCM that is directly proportional to the throttle plate position. The TP sensor is mounted on the side of the throttle body and is connected to the throttle plate shaft.
The TP senses the throttle movement and position and transmits an appropriate electrical signal to the PCM. These signals are used by the PCM to adjust the air/fuel mixture, spark timing and EGR operation according to engine load at idle, part throttle, or full throttle. The TP sensor has 2 versions, an adjustable and a non-adjustable; the difference being elongated mounting holes that allow the rotary sensor to be turned slightly to adjust the output voltage. The rotary TP sensor with round mounting holes are not adjustable.
See Figure 1
See Figure 2
- Disconnect the negative battery cable.
- Disconnect the wiring harness from the sensor.
- Check resistance between terminals TP (br/w wire) and the VREF (gy/w wire), on the TP sensor.
Do not measure the wiring harness connector terminals, rather the terminals on the sensor itself.
- Slowly rotate the throttle shaft and monitor the ohmmeter for a continuous, steady change in resistance. Any sudden jumps, or irregularities (such as jumping back and forth) in resistance indicates a malfunctioning sensor.
- Reconnect the negative battery cable.
- Check sensor signal voltage between the TP SIG and SIG RTN terminals. Turn the ignition switch ON and using the DVOM on voltmeter function, measure the voltage between terminals 89 and 91 of the breakout box. The specification is 0.17-0.40 volts.
- If the voltage is outside the standard value or if it does not change smoothly, inspect the circuit wiring and/or replace the TP sensor.
With ignition OFF , disconnect the TP sensor connector. Measure voltage between sensor connector terminals SIG RTN and VREF . The voltage reading should be 4.0-6.0 volts. If not, replace the sensor.
REMOVAL & INSTALLATION
See Figure 3
- Disconnect the TP sensor wiring harness.
- On 5.0L and 5.8L engines, it may be necessary to remove the throttle body. On all other engines, proceed to the next step.
- Disconnect the wiring from the sensor.
- Matchmark the TP sensor and throttle body. Remove the 2 retaining screws and the sensor.
- On 5.0L and 5.8L engines, position the TP sensor so that the pigtail points toward the IAC valve.
- Secure the TP sensor to the throttle body with the retaining screws. Tighten to 18-27 inch lbs. (2-3 Nm) on 4.9L engines or 11-16 inch lbs. (1.2-1.8 Nm) on 5.0L/5.8L engines.
- If applicable, install the throttle body.
- Connect the wiring.
- Connect the negative battery cable.