Chevy Silverado Brake Light Troubleshootingby Dan Ferrell
Chances are the cause of the defective light or brake lights circuit on your Chevy Silverado is a simple problem. Moreover, you can blame most of these problems on little or no maintenance, according to James E. Duffy in "Modern Automotive Technology." Of course, there is also the possibility of a hidden short or open somewhere in the middle of the circuit. But before you begin pulling wires, start troubleshooting at the most obvious places to get your lights back in working order.
Check a Single Non-working Light
You can start your troubleshooting at the malfunctioning brake light assembly, if only that light seems broken. Remove the cover and check the light bulb for an open filament or damage. Closely examine the socket and connections for corrosion, loose or broken wires. Test the black wire/ground connection using a jump wire to bridge the ground at the light socket to a good chassis ground on the vehicle and ask a helper to operate the brake lights. After you confirm that the bulb, socket and connections are in good shape and there is no electrical current reaching the bulb, begin tracing and testing the electrical wires back to the source using a test light to find a possible short or open.
Check the Brake Lights Circuit
Start at the fuse box under the hood and make sure the brake lights fuse is not blown, that the terminals are free of corrosion and that the connections are tight. Then check the brake light switch on the bake pedal arm. Back probe the switch terminals with a test light. Only one of the switch terminals should turn on the test light. When you depress the brake pedal, both switch terminals should turn on the test light. If only one of the wires turns on the test light, unplug the switch and jump the two connections at the connector. If the brake lights come on, replace the switch. When there is no current reaching the switch, follow the orange wire back to the under hood fuse block and look for a possible open or short. If electrical current is reaching the switch but the lights are not working, even if the switch is in good condition, follow the current flow with your test light to the stop lamps and look for a possible open or short in the circuit. A blue wire connects the brake lights switch to the rear lamps junction block. A brown wire and another light blue wire connect the rear junction block to the left rear stop lamp; a brown/white wire and another light blue wire connect the rear junction block to the right rear stop lamp. Black wires at the lamps provide the ground connections.