Circuit/System Description
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The exhaust gas temperature sensors are variable resistors that measure the temperature of the exhaust gas at the inlet and outlet of the diesel particulate filter (DPF). The engine control module (ECM) supplies a bias 5V signal to the EGT signal circuit, and supplies a ground to the low reference circuit. When the EGT sensor is cold, the sensor resistance is low. When the EGT temperature increases, the sensor resistance increases. With high sensor resistance, the ECM detects a higher voltage on the EGT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the EGT signal circuit.