Visual Inspection
WARNING: This page is about a different car, the 1997 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
Before entering diagnostics, perform a comprehensive visual inspection of component integrity, connector damage, improper connector mating, poor wire to terminal connections, wire chafing, damaged terminals, and dirty or corroded terminals. The most common problem is faulty wiring and connections.