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 signal circuit

The Powertrain Control Module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also 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. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM 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). Certain vehicle models will also use the MAP sensor 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 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 P1120, P1125, P1220, P1221, P1275, P1276, P1280, P1281, P1285, P1286, P1514, P1515, P1516, P1517, or P1518 are not set.
^ The engine is running.
^ The throttle angle is 0 percent when the engine speed is less than 1,200 RPM.
^ The throttle angle is less than 20 percent when the engine speed is more than 1,200 RPM.

CONDITIONS FOR SETTING THE DTC
The MAP sensor voltage is more than 4.9 volts for more than 2 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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.
^ Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS
^ Inspect the MAP sensor vacuum source for leaks, for restrictions, or for poor connections.
^ Inspect any circuitry that is suspected of causing an intermittent. refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-11:

Steps 12-16:

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, the 5-volt reference circuit is either shorted to ground or is 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 can aid in locating an intermittent condition.