Diagnostic Aids

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Ask about the customer's driving habits, trailer towing, etc. Trailer towing should occur in tow haul mode.
Ensure the engine cooling system is functioning normally.