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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1037 (Engine Controls Diagnosis - 6.6L (LLY) (DTC P0016 To DTC P0237)) >> Diagnosis >> DTC P0116 >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the signal circuit and a ground for the low reference circuit. When the engine coolant temperatures are low, the resistance is high. When the engine coolant temperatures are high the resistance is low. The ECM uses this high side coolant rationality test to determine if the ECT input is skewed high. The ECM will record the amount of time the engine is OFF. At restart the ECM will compare the temperature difference between the ECT and intake air temperature (IAT). Before failing this diagnostic, the ECM will perform the calculation to determine the presence of a block heater. If the temperature difference is not within the calculated range, after the predetermined engine OFF time, DTC P0116 sets.

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