Envoy 2WD V6-4.3L VIN W (1998)
Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
DESCRIPTION
The Throttle Position (TP) sensor is a potentiometer. The TP sensor is connected to the throttle shaft on the throttle body. By monitoring the
voltage on the signal line, the VCM 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 4.0 volts.
PURPOSE
The VCM 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. This may cause an unstable idle because the VCM detects the throttle is moving.
When the VCM detects a malfunction with the TP sensor circuits, the following Diagnostic Trouble Code (DTC)s will set:
^
DTC P0121 circuit performance
^
DTC P0122 circuit low.
^
DTC P0123 circuit high.
^
DTC P1121 intermittent circuit high.
^
DTC P1122 intermittent circuit low.
Refer to System Diagnosis / Diagnostic Tables for testing information.
