Circuit Description

The manifold absolute pressure (MAP) sensor that resides in the engine intake manifold is integrated with the intake air temperature (IAT) sensor 2. The purpose of this integrated sensor is to measure the following:

• The atmospheric pressure and the vacuum or the reduced pressure that exists under different operating conditions in the engine intake manifold
• The supercharged air pressure that exists under high load or wide open throttle conditions in the engine intake manifold
• The IAT 2 after the supercharger and the intercooler as it enters the engine intake manifold
• The IAT 2 after the supercharger bypass valve and the intercooler as it enters the engine intake manifold

The MAP/IAT sensor 2 has the following types of circuits:

• A powertrain control module (PCM) supplied and regulated MAP 5-volt reference circuit
• A PCM supplied ground for the low reference circuit that is shared by the MAP and the IAT sensor 2
• A MAP sensor signal circuit that supplies a voltage input to the PCM
• A PCM supplied 5-volt, IAT signal circuit

The diaphragm within the MAP sensor responds to all of the various pressure changes in the intake manifold, and provides a signal voltage to the PCM on the signal circuit, relative to those pressure changes.

The PCM monitors the MAP sensor signal for voltage that is outside of the normal range of a properly operating sensor. If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets.