Circuit/System Description

The engine control module (ECM) monitors three sensors' signals to calculate the efficiency of the charge air cooler (CAC):

• Intake air temperature (IAT) sensor 1
• IAT sensor 3
• Charge Air Cooler Temperature Sensor

The Charge Air Cooler Temperature Sensor, the IAT sensor 3 and the IAT sensor 1 are variable resistors. The ECM supplies 5 V to the signal circuits and a ground for each sensor's low reference circuit. The ECM monitors the Charge Air Cooler Temperature Sensor and the IAT sensor 1 signals to calculate the temperature of the fuel air. The ECM monitors the CAC sensor and IAT sensor 3 signals for excessively high or low voltages or for voltage that is not in correlation with the other sensor's start up signal.

The sensors are listed in direction of the intake air flow, below:

• The IAT sensor 1 is part of the Mass Air Flow (MAF/IAT) sensor assembly, located in the air cleaner assembly cover. Its signal is used by the ECM to calculate Ambient Temperature.
• The IAT sensor 3 is located in the outlet duct from the turbocharger. Its signal is used by the ECM to measure the temperature of the intake air going to the CAC inlet.
• The Charge Air Cooler Temperature Sensor is located in the CAC outlet duct before the throttle body assembly. Its signal is used by the ECM to measure the temperature of the intake air leaving the CAC.