Grand AM V6-3.4L VIN E (2001)
Manifold Absolute Pressure (MAP) 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 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 signal voltage. With high manifold absolute pressure such as ignition ON, with the engine OFF or wide-open throttle, the
PCM should detect a high signal voltage. Certain vehicle models will also use the MAP sensor 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. IP the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 will set.
DIAGNOSTIC AIDS
Inspect for the following:
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Restrictions in the MAP sensor vacuum source
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MAP sensor seal missing or damaged
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Vacuum hoses disconnected, damaged, or incorrectly routed
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Intake manifold vacuum leaks
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Vacuum leaks at the throttle body
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Vacuum leaks at the Exhaust Gas Recirculation (EGR) valve flange and pipes
TEST
Steps 1-4
