Truck is F 550, 2000 model with after market RV bed. The right rear signal light worked intermittantly. While checking the bulb and housing I noticed a bare section of wire going to the signal light. I could move the wires and the light would flash. As I was reaching for the wire, to tape up the bare spot.... the bare section touched the bed, just for a split second. I saw a small spark when it touched. I completed taping the bare spot and when I returned to the cab, the right signal was on and flashing very quickly. The left signal workes just fine. The right front signal light flashes rapidly and the right rear does not flash. I have disconnected the right rear signal wire all the way to the cab and the right signal pulse is very rapid (no power to the right rear). All the fuses are OK. I doubt that the right signal wire is shorted to ground. I suspect there is a set of contact points in a relay that fused itself shut when the wire touched ground. Suggestions?

 

Welcome to FTE, hobohilton.

When you put your right turn signal on, your front flashes quickly, and the rear not at all? I think your rear bulb is burnt out. Try taking a look at it to see if it looks okay, or just replace it.

 

That was my first move. Then I found I had no power going to the right rear bulb even though the front right bulb would flash. Next I thought possibly the wire going to the right rear signal had simply shorted out on the bed, somewhere, which made for the rapid flash pulse.... I took the wire to the right signal loose where the wires for the signal (and all other bed lights) actually leave the wire loom in the chassis, just behind the cab. I'm using a 12 volt test light and get no power in the loom behind the cab for the right rear signal. I have power for tail lights, left signal, left brake and left emergency flasher. Nothing for the right signal/brake. Could there be a stuck set of contacts in the signal light switch in the steering column?