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Monday, October 26, 2009

Running Light Problem

I have a Jayco 30-foot travel trailer. I cannot get the running lights to work at all. I have tested the connection from my vehicle and it tests okay. Any common things I can look for? The brake lights and turn signals work just fine. I have looked at all the bulbs and they too seem okay. Will a burned out bulb break a complete circuit?
Mike, (Livonia, MI)

Mike, if you are sure the tow vehicle plug is wired to match exactly the configuration on the trailer plug, then I’d check the ground circuit carefully. Be sure there is a good ground between each lamp in the circuit and the frame or exterior skin of the trailer. Evidently there is a good ground connection between the tow vehicle and the trailer since the turn signals and stop lamps work; (by the way, it’s the same filament in those bulbs for both the turn signals and the stop lamps).

On a travel trailer, the running lights are wired in parallel which means one bulb could go out and the rest will still work, but I’m guessing you have an open circuit in that circuit before the voltage even reaches the first lamp. One or two lamps not working is one thing, but no lamps working leads me to believe a fuse has blown on the trailer or there is an open in that circuit. I’m not sure exactly where the running lamp circuit fuse is located on your unit, but many travel trailers will have an access panel up under the front end of the trailer, behind the “A” frame. Just follow the electrical cable and see where it disappears into the trailer. Some fuses may be located behind a panel secured to the underbelly pan. In some cases the fuses may be located inside the trailer.

As an additional troubleshooting step you can apply 12-volts DC from a small battery charger or other 12-volt source directly to the bulb contact on one of the two front corner running lamps. If the remaining lamps light up, then the problem is between the electrical connector on the “A” frame and that first lamp in the circuit.


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