Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
The power supply cord will read open due to an internal thermal switch if the ambient temperature is above -18°C (0°F).
- Test the engine coolant heater for an open or short to ground.
- If open or shorted, replace the heater.
- If the heater tests normal, replace the coolant heater power cord.