Rodeo LS 4WD V6-3.2L (1998)
Throttle Position Sensor: Description and Operation
DESCRIPTION AND OPERATION
The throttle position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle body. The Powertrain Control Module (PCM)
monitors the voltage on the signal line and calculates throttle position. As the throttle valve 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 valve opens, the output increases so that
at wide open throttle (WOT), the output voltage should be above 4 volts.
The PCM calculates fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor may cause intermittent bursts of fuel
from an injector and unstable idle because the PCM thinks the throttle is moving. A hard failure in the TP sensor 5-volt reference or signal circuits
will set either a DTC P0122 or DTC P0123. A hard failure with the TP sensor ground circuit may set DTC P0123 and DTC PO112. Once a DTC
is set, the PCM will use an artificial default value based on engine RPM and mass air flow for the throttle position, and some vehicle performance
will return. A high idle may result when either DTC PO122 or DTC PO123 is set. The PCM can detect intermittent TP sensor faults. DTC P1121
or DTC P1122 will set if an intermittent high or low circuit failure is being detected. The PCM can also detect a shifted TP sensor. The PCM
monitors throttle position and compares the actual TP sensor reading to a predicted TP value calculated from engine speed. If the PCM detects an
out-of-range condition, DTC PO121 will be set.
