XJ-12 (X300) V12-6.0L (1995)
Throttle Position Sensor: Testing and Inspection
Monitoring Procedure
Throttle Position Sensor
Fig. 1 TP Sensor
Monitoring Procedure
The sensor output is monitored under steady driving conditions. The output is compared to the expected value (which is mapped against engine
load and RPM). If the difference between these values is above a threshold then the range / performance failure judgement is made. The diagnostic
trouble code (DTC) is stored if the failure judgement is made on two successive trips.
Throttle position is detected by the Throttle Position Sensor (TPS) which reports to the engine control module (ECM). The closed throttle
position switch (idle switch) is integral to the throttle position sensor.
Structure of TPS
The throttle position sensor is a potentiometer. It is installed on the throttle cable bracket which is connected to the throttle body. As throttle
position changes, the TP Sensor sends a voltage signal to the ECM.
Closed Throttle Position Switch
Monitoring Procedure
This diagnostic operates during repeated vehicle acceleration and deceleration. If the ECM has seen five accelerations (open throttle, to above 20
mile 1 hour) and decelerations (closed throttle, to a stop) without a change of state of the idle switch, then the switch is judged to be faulty. The
particular DTC depends on the output the switch gives during the failure judgement. The diagnostic trouble code (DTC) is stored if the failure
judgement is made on two successive trips.
NOTE: The CTPS / idle switch comprises part of the throttle position sensor assembly.