Can anyone provide help for wiring the "add-on brake light" on a cap/ for the back of a truck. Using the wiring in either of the rear lights works until you turn on the respective turn signal--then the brake light blinks with the turn signal.

There has to be a way . . . . . h e l p ! Thanks

sounds like you also wired the turn signal wire in with the brake light. is the add on brake light a 2 or 3 wire light assembly? some are just for brakes (singal filament bulb and 2 wires) and others are for brake and running lights (dual filament bulb and 3 wires).

The add-on light is a single filament type, two wires--should only light with brakes applied.

The light works when connected to the brake light wire in the tail light of the truck. Problem is, that the turn signal also pulses that brake light wire in the tail light. So if I hook up to the left tail light, the add-on brake light flashes when the left turn signal is used and if I hook to the right tail light, the add-on brake light flashes when the right turn signal is used (that is if the brake and turn signal are active at the same time).

is your brake light bulb in your tail light assembly a dual filament bulb?

i have a 1998. i am going to check now.

It's more than a "dual filament" bulb--it has a filament for the parking lights, and several filaments for the brake light and, I guess, the turn signal. It's a sophisticated looking bulb.

i have a 3rd brake light on my truck and the third brake light doesnt come on when the running lights are on. it is only a brake light.