Manifold Absolute Pressure Sensor: Description

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

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 the following circuits:

A 5-volt reference circuit.
A 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 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 MAP such as during idle or deceleration, the PCM should detect a low signal voltage. With high MAP such as ignition ON, with the engine OFF or Wide Open Throttle (WOT), the PCM should detect a high signal voltage. Certain vehicle models will also use the MAP sensor to calculate the Barometric (BARO) pressure when the ignition switch is turned to RUN position, 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. If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 will set.