Manifold Pressure/Vacuum Sensor: Testing and Inspection

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR DIAGNOSIS

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:
- 5-volt reference circuit
- Low reference circuit
- MAP sensor 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 MAP sensor 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). 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 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 sets. If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 sets

TEST DESCRIPTION

Steps 1-3:

Steps 4-6:

Steps 7-11:

Steps 12-14:

Steps 15-17:

Steps 18-24:

The number below refers to the step number on the diagnostic table.
4. This step tests the MAP sensor's ability to correctly indicate BARO.