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.

A short to ground on the 4 low indicator control circuit will cause the 4 low indicator to remain on at all times.
An open or high resistance on the 4 low indicator to be inoperative during the 2 second bulb check.
An open in the indicator dimming control circuit will cause the 2 High, 4 High and 4 Low mode indicators to be inoperative during the 2 second bulb check.