Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
- Ignition ON, verify the scan tool hood position parameter displays Open.
- If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Test the thermostat for correct operation. Refer to Thermostat Diagnosis .
- Test the engine cooling system for overheating. Refer to Engine Overheating .
- Inspect the water pump and coolant flow for correct operation. Refer to Water Pump Replacement (RPOs LY2/LC9/LY5/LMG/LFA) or Water Pump Replacement (RPOs LY6/L76/L92) .
- Inspect the engine for worn/leaking/cracked cylinder heads and engine block. Refer to Coolant in Combustion Chamber and Coolant in Engine Oil .