duraluminum

Brake lights work normal without running lights on but when I turn on the running lights both filaments in the brake light bulb comeon. Also factory cruise control works until running lights are turned on. All bulbs seem fine. There are no alarm systems or trailer wiring boxes on truck. There is trailer wiring spliced into the wires at the back of truck but they seem to be working fine until running lights are turned on.

wyoming9

iTrader: (1)

Clean your sockets and bulbs it might be you have a poor ground and it is grounding through the brake lights.

I use a fitting brush to clean the sockets and scotch brite pads to clean the blubs some times you are unable to see the corrosion with your naked eye .

Contact cleaner works as well

The cruise control sees it as the brakes are being applied so won`t engage.

Bills86e

The brake light switch is sensitive to adjustment. If the brake light stays on, the circuit is closed. (or switch is bad)

This may cause battery failure.