Throttle Position (TP) Sensor

Discovery & Range Rover

TP sensor is a variable resistor mounted on the throttle body and connected directly to the throttle shaft. TP sensor signal informs ECM of actual throttle position and rate of change in throttle position. ECM cross checks TP sensor output with Mass Airflow (MAF) sensor output. If values from these two sensors do not agree and fuel injection feedback indicates correct air/fuel mixture, ECM assumes MAF sensor is correct and TP sensor has failed.
TP signal is also supplied to the Electronic Automatic Transmission Electronic Control Unit (EAT ECU) from the ECM using Controller Area Network (CAN) communication link. EAT ECU uses throttle position data to determine the correct point for gear shifts and acceleration kickdown. The ECM also supplies the Self-Leveling and Anti-Lock Brake System (SLABS) ECU, and Active Cornering Enhancement (ACE) ECU with TP sensor information as a Pulse Width Modulation (PWM) signal. If TP sensor signal fails, ECM uses a default value derived from engine load and speed. A fault is indicated by illumination of the MIL. A TP sensor failure may result in a poor throttle response and degraded engine performance, emission control failure, closed loop idle speed control inoperative, automatic transmission kickdown inoperative and/or incorrect altitude adaptation.

Fig 1: Locating Computerized Engine Control Components (Discovery)

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Fig 2: Locating Computerized Engine Control Components (Freelander)

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Fig 3: Locating Computerized Engine Control Components (Range Rover - 1 Of 2)

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Fig 4: Locating Computerized Engine Control Components (Range Rover - 2 Of 2)

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