Troubleshooting Lights on Haulmark Passport Enclosed Cargo Trailer

Updated 06/20/2018 | Published 06/18/2018

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Question:

I have a haulmark passport enclosed trailer. My tail lights and running lights will not work with the dome light turned on. If I turn on dome light the light will flash and then running lights and tail lights go out. I have to wait a few minutes before turning lights back on. Tail and running lights work fine if dome is left off. What is in the dome light that would have to cool before lights will come back on?

asked by: Dave

Expert Reply:

Your trailer's stop/turn/tail lights are powered by the lighting signal circuits from your tow vehicle while the dome light would be powered by the 7-way's auxiliary +12V circuit. Since both work, but not at the same time, odds are your issue is related to grounding. All powered circuits on the trailer ultimately share the same ground connection (to the vehicle battery) and it is possible that if the main trailer ground has now corroded it may no longer be able to support all circuits at once.

I suggest finding the main ground wire on the trailer which should have a ring terminal that is affixed to the trailer frame. Disconnect this ring terminal and try sanding and/or cleaning off that spot to expose clean bare metal. That new clean connection can be protected from future corrosion by applying dielectric grease like # 11755.

There is probably an auto-resetting circuit breaker like # PK54220PL on the dome light circuit that restores operation once it has cooled.

You can easily reduce total trailer power consumption quite a bit by replacing incandescent light bulbs with LED equivalents. We have such replacement LED "bulbs" for many popular incandescent type bulbs found in trailers. LEDs use about 1/10th of the power required by standard bulbs and if you were to replace some or all regular bulbs with their LED equivalents you could greatly reduce power draw on your vehicle wiring.

The linked page displays all LEDs; just find your bulb numbers on your existing bulbs and on the page click on that number to see replacement LEDs that can go right into the existing fixtures. For example, the bulb type 1157 is quite common; we offer replacements such as # DI52VR.