Document ID# 690344
2001 Chevrolet Cavalier (CNG)
The throttle position (TP) sensor is a potentiometer. The gasoline Control Module (VCM / PCM or ECM) supplies about 5 volts on the TP sensor reference voltage circuit. The gasoline Control Module also supplies a ground circuit to the TP sensor. When the throttle is depressed the TP signal voltage rises to near the supplied 5 volts. As the throttle is released, the TP signal voltage drops to around 0.6 volts. The gasoline Control Module and the AF ECU monitor the TP signal circuit voltage and determine the angle (or opening) of the throttle blade.
The manifold absolute pressure (MAP) sensor is a pressure sensor. The gasoline Control Module (VCM / PCM or ECM) supplies about 5 volts on the MAP sensor reference voltage circuit. The gasoline Control Module also supplies a ground circuit to the MAP sensor. When manifold vacuum is low the MAP signal voltage rises to near 4.5 volts. As manifold vacuum increases the MAP signal voltage drops to around 1 volt. The gasoline Control Module and the AF ECU monitor the MAP signal circuit voltage and determine the vacuum within the intake manifold.
Certain vehicle models will also use the MAP sensor in order to determine the barometric pressure when the ignition switch is turned ON and the engine is NOT cranked. This BARO reading may also be updated whenever the engine is operated at wide open throttle.
This DTC is used to indicate a MAP sensor signal voltage that does not change when TP sensor voltage changes.
Conditions for Running the DTC
• The engine is operating on alternative fuel.
• The engine has been operating for greater than 5 seconds.
• No AF ECU DTCs are set. DTCs P1215, P1432 and P1433 may be set.
• TP sensor angle is less than 70 percent.
Conditions for Setting the DTC
The AF ECU monitors that the MAP sensor pressure changes less than 6 kPa when the TP sensor angle changes by greater than 20 percent.
Action Taken When the DTC Sets
• A first failure of this DTC will NOT illuminate the MIL and will store as Last Test Failed but not as History.
• The AF ECU will illuminate the MIL and store the DTC as History after TWO consecutive drive trips that the diagnostic runs and fails.
• The AF ECU will record operating conditions at the time the DTC sets. This information will be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC
• The Last Test Failed status will clear when the DTC runs and passes.
• The AF ECU will turn OFF the MIL after 3 consecutive drive trips that the DTC runs and passes.
• The History status will clear after 40 consecutive WARM-UP cycles with NO failures of ANY DTC.
• All DTC Information can be cleared using a scan tool.
• Interruption of Control Module (AF ECU / VCM / PCM or ECM) power or ground MAY clear DTC Information. Clearing DTC Information with this method is inconsistent and should not be performed.