P0108

DTC P0108

CIRCUIT DESCRIPTION




The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:
- A 5-volt reference circuit
- A low reference circuit
- A MAP sensor signal circuit

The engine control module (ECM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The ECM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the ECM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The ECM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The ECM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The ECM monitors the MAP sensor signal for voltage outside of the normal range. If the ECM detects a MAP sensor signal voltage that is excessively high, DTC P0108 will set.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0122 or P0123 are not set.
- The TP Angle parameter is less than 2 percent when the Engine Speed parameter is less than 1,600 RPM.OR
- The TP angle parameter is less than 10 percent when the Engine Speed parameter is more than 1,600 RPM.

CONDITIONS FOR SETTING THE DTC
The ECM detects that the MAP sensor voltage is more than 4.2 volts for 3 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

TEST DESCRIPTION

Steps 1 - 9:

Steps 10 - 15:

The number below refers to the step number on the diagnostic table.
4. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records can aid in locating an intermittent condition.