Terraza FWD V6-3.5L VIN 8 (2005)
Manifold Pressure/Vacuum Sensor: Testing and Inspection
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR DIAGNOSIS
CIRCUIT DESCRIPTION
The manifold absolute pressure (MAP) sensor responds to changes in 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 MAP
sensor 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 MAP sensor signal voltage. With high MAP, such as ignition ON, engine OFF or wide open throttle (WOT), the PCM should detect a
high MAP sensor signal voltage. 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 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 low, DTC P0107 sets. If the PCM
detects a MAP sensor signal voltage that is excessively high DTC P0108 sets.
DIAGNOSTIC AIDS
Poor idle characteristics may be caused by uncontrolled fueling due to an open or high resistance in the HO2S 1 low signal circuit. Before replacing
any component, ensure that this condition does not exist.
TEST DESCRIPTION
