Theory Of Operation

The Powertrain Control Module (PCM) monitors three separate air temperature sensors to determine the Charge Air Cooler (CAC) efficiency and fuel delivery. The component names, locations and correlating DTCs are shown in the illustration and table below. The Intake Air Temperature and Inlet Air Temperature Sensors are standalone typical two wire sensors that are supplied a 5 volt signal and sensor ground by the PCM. The Charge Air Cooler Temperature Sensor and Manifold Absolute Pressure Sensor are combined into one component (TMAP). The 5 volt supply circuit is only used for the pressure sensor portion of the TMAP which operates like a typical three wire MAP Sensor. The integrated temperature sensor portion shares the common sensor ground circuit with the pressure sensor. The internal pressure sensor and temp sensor each supply feedback to the PCM through dedicated signal circuits.

The PCM internally monitors the signal circuit voltages and performs diagnostics of the sensors and circuitry. If the signal voltage reads above the high calibrated threshold, or below the low calibrated threshold, a circuit high or low fault is set. During cold start conditions the PCM also performs rationality diagnostics by comparing the air temperature sensor values to the Ambient Air Temperature (AAT) and Engine Coolant Temperature (ECT) Sensors.