P0108

CIRCUIT DESCRIPTION
The Manifold Absolute Pressure (MAP) sensor responds to changes in the 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 during ignition ON, engine OFF or wide-open throttle, the PCM should detect a high MAP sensor signal voltage. This MAP sensor will indicate pressure between 10-104 kPa. The MAP sensor is also used in order to calculate the Barometric Pressure (BARO) when the ignition switch is turned ON, with the engine 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 start-up coolant temperature. The length of time ranges from 2 minutes at less than 30°C (22°F) to 1 second at more than 30°C (86°F).
^ The throttle angle is less than 2 percent when engine speed is less than 1,500 RPM.
^ The throttle angle is less than 10 percent when the engine speed is more than 1,500 RPM.

CONDITIONS FOR SETTING THE DTC
The MAP sensor signal voltage is more than 4.2 volts for 7 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ First failure:
- The MIL is not turned ON.
- A DTC is stored in memory under Failed Last Test.
- The Failure Records are stored.
^ Second consecutive drive cycle with a failure:
- The MIL is turned ON.
- A DTC is stored in memory under history.
- The Freeze Frame data is stored.
- The Failure Records are stored.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after the third consecutive trip the diagnostic has run and passed.
^ The history DTC will clear if the fault conditions have not been detected for 40 warm-up cycles.
^ A scan tool can be used to clear DTC information.

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

TEST DESCRIPTION

Steps 1-8:

Steps 9-16:

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 sensor 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/Failure Records data can aid in locating an intermittent condition.