Visual/Physical Inspection

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2005 Isuzu Ascender, 2005 GMC Envoy XUV, 2005 GMC Envoy XL, 2005 GMC Envoy, and 2005 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

Inspect for aftermarket devices which could affect the operation of the systems. Refer to Checking Aftermarket Accessories in Wiring Systems.
Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.