Theory Of Operation
WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The Exhaust Temperature Sensors are used by the Powertrain Control Module (PCM) to monitor the engine exhaust temperatures in the aftertreatment system. The Exhaust Temperature Sensors are thermistors and change resistance based on the temperature being measured. The Exhaust Temperature Sensors receive a 5-Volt signal from the PCM and share a sensor ground. The PCM monitors the change in signal voltage and converts this to a temperature value. The PCM illuminates the MIL lamp immediately when the diagnostic runs and fails.