P1107 CHEVROLET - Manifold Absolute Pressure Sensor Circuit Intermittent Low Voltage
- Manifold Absolute Pressure (MAP) sensor harness is open or shorted
- Manifold Absolute Pressure (MAP) sensor circuit poor electrical connection
- Engine rough idle
- Engine hesitation
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.
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