P0108

CIRCUIT DESCRIPTION
The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure which gives an indication of the engine load. The MAP sensor has a 5 volt reference circuit, a low reference circuit, and a signal circuit. The Powertrain Control Module (PCM) supplies 5 volts to the MAP sensor on the 5 volt reference circuit and provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the signal circuit which is relative to the pressure changes in the manifold. With low manifold absolute pressure, such as during idle or deceleration, the PCM should detect a low MAP sensor signal voltage. With high manifold absolute pressure, such as with the ignition ON and the engine OFF or at Wide-Open Throttle (WOT), the PCM should detect a high MAP sensor signal voltage. Certain vehicles will also use the MAP sensor to calculate the Barometric Pressure (BARO) when the ignition switch is turned ON, and the engine is OFF. The BARO reading may also be updated whenever the engine is operated at Wide-Open Throttle. The PCM monitors the MAP sensor signal for voltage outside of the normal range. If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 will set.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0121, P0122, or P0123 are not set.
^ The engine has been running for a length of time that is determined by the startup engine coolant temperature. The length of time ranges from 2 minutes at less than 30°C (22°F) to 0.5 second at more than 30°C (86°F).
^ The throttle angle is less than 2 percent.
^ The engine speed is less than 3,000 RPM.

CONDITIONS FOR SETTING THE DTC
The MAP sensor voltage is more than 4.2 volts for approximately 10 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The PCM will store the conditions which were present when the DTC set as Freeze Frame and Failure Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the Malfunction Indicator Lamp (MIL) OFF after 3 consecutive drive trips that the diagnostic runs and passes.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
^ Inspect the MAP sensor vacuum source for leaks, restrictions, or poor connections.
^ If an intermittent condition exists, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-3:

Steps 4-16:

The numbers below refer to the step numbers on the diagnostic table.
2. The MAP sensor 5 volt reference circuit is shared with other sensors. If DTC P1635 is set, this indicates that the 5 volt reference circuit is either shorted to ground or shorted to voltage and should be diagnosed first. The short may be on another sensors 5 volt reference circuit.
4. Operate the vehicle within the same conditions as when the DTC failed. If you cannot duplicate the DTC, the information included in the Freeze Frame and Failure Records can aid in locating an intermittent condition.