Riviera V6-3.8L SC VIN 1 (1995)
Throttle Position Sensor: Testing and Inspection
SCAN TOOL TESTING
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 problem in the TP sensor 5 volts reference or signal circuits
should set either a Diagnostic Trouble Code (DTC) P0122 or DTC P0123. A problem with the TP sensor ground circuit may set DTCs P0123 and
P0117. Once a DTC is set, the PCM will use an artificial default value based on Mass Air Flow (MAF) for TP sensor and some vehicle
performance will return. A high idle may result when either DTC P0122 or DTC P0123 is set. See: Powertrain Management/Computers and
Control Systems/Testing and Inspection
The Tech 1 scan tool displays throttle position in volts and percentage of throttle blade opening. The value should display between about 0.3 - 0.9
volt, with throttle closed and ignition "ON," or at idle. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle
(WOT) (about 4.6 volts). The Tech 1 scan tool display should be 0% when the throttle is closed.
