Theory Of Operation
WARNING: This page is about a different car, the 2014 Dodge Journey. However, it is still accessible from the selected car via links, so may be relevant.
Ambient Air Temperature (AAT) sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. The AAT reading is a bussed message from the Body Control Module (BCM) to the Powertrain Control Module (PCM). Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors are compared. The AAT sensor is a variable resistor that measures the ambient air temperature. The BCM supplies a 5 Volt reference and a ground to the sensors low reference signal circuit. When the AAT is low, the sensor resistance is high. When the AAT is high, the sensor resistance is low.