No 3rd brake light

[Cummings]

This one may test you guys. My 2004 2500 has lost it's 3rd brake light. Bulb is good, no power to socket. Fuse is good, no wires chaffed. Possibly a product of this is the fact that there is a pulsing in my trail brake circuit, which causes the trailer brakes to pulse off and on very briefly for the entire time the trailer is connected, even if the truck is shut off. The brake controller is a Prodigy, and I put in a new one, thinking the controller was bad. I haven't yet had a chance to look at the brake light switch, but any other ideas? Thanks.

 

[Prairie Dog]

Did it ever work?
I installed a canopy on my truck when it was new and unplugged the third brake light behind the fixture. Maybe someone did the same to your truck?

 

[Cummings]

The 3rd brake light worked when we bought the truck new. Both items seemed to happen at the same time, so I'm sort of guessing that they are inter related.