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 a 5-volt reference circuit, low reference circuit and a MAP sensor signal circuit.

The Engine Control Module (ECM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The ECM also provides a ground on the low reference circuit. The MAP sensor provides a signal to ECM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The ECM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The ECM should detect a high signal voltage at a high MAP, such as ignition on, with 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 is on, with engine off. The BARO reading may also be updated whenever the engine is operated at WOT. The ECM monitors the MAP sensor signal for voltage outside of the normal range.

ECM calculates a predicted value for the MAP sensor based on Throttle Position (TP) and engine speed. The ECM then compares the predicted value to the actual MAP sensor signal. If ECM detects that the MAP sensor signal is not within the predicted range, DTC P0105 sets.