1. Trailer tail lights and brake lights are the same when both are on. You cannot tell the difference between the two if the lights are on and the brake is engaged. 2. Which wire are the inside lights of the trailer on...is it the trailer battery feed?
Expert Reply:
With the running lights on, the lamp should get brighter when the brake is applied. If it does not, check to make sure that lamp is properly grounded to the trailer frame, and that the connections are secure and not corroded. These functions use the same bulb. The trailer interior lights are usually wired into the running light circuit. They are sometimes wired into the accessory (battery feed) as well.
expert reply by: Mike L
