I agree with all that has been written above. Any pulsating light or brake assembly (when directionals are applied) will be a reflection of a bad ground someplace, allowing a different, unwanted path for the current to return to "Ground". Remember the basic rule of electricity, "Electricity will always follow the path of least resistance".

I only want to add, as one who has recently rewired an 18 foot open car trailer, it's a little time consuming, but really worth it. Traditionally, trailers are wired with "Scotch connectors" (a cheap method of taping into an existing wire with minimum effort), or what ever thay are called, that leave the connnections exposed to the elements (read corrosion). After a few years have passed, the owner will chase wiring problems from one part of the trailer to another.

I bought (NAPA) 5-wire loom in two 25 foot lengths (soldered together), strung one length down one side from the plug (front of trailer), across the rear, and another up the other side to the foreward most light. The wire is color coded for typical wires of the trailer, and I had an extra wire in the loom for the back-up lights which we installed upon purchase oh-so-many years ago. Very handy when returning at oh-dark-O'clock.

Using the wire loom, it gave the option to have directional lights on any location on the body of the trailer, not to mention axillary lights (Back-up lights) mounted anywhere. After the wire is in position, just tap into the appropiate color for that particular light (see next sentence). The key to the success of the job (and the most time consuming) is to solder all connections and cover with shrink tubing. Of course, if the chassis of the trailer is also used for ground (almost all are!), re-establish the ground connection with wire brush, sanding, good connections and dielectric grease.

This will also give you opportunity to check the wiring of the brake assemblies, which were also connected with scotch connectors.

If you devote a Saturday to this project, you will be rewarded with consistant lighting and braking for years to come. Braking efficiency is synonomous with Safety.

Good racing.

Bill