How to Access 5th Wheel Taillight Wiring for Installing Wiring Harness

Updated 03/23/2017 | Published 03/22/2017

Products Featured in This Question

Hook Probe Circuit Tester

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$13.33

Hopkins Endurance 4-Way Flat Trailer Connector w/ 48" Harness and Ergonomic Pull

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$9.63

Question:

How do I get to the wiring on the tail lights of a fifth wheel so I can wired up for to pull a trailer behind a fifth wheel Coachman

asked by: Mike

Expert Reply:

Usually, it will be necessary to remove interior trim panels to access the taillight wiring of a 5th wheel. If your particular trailer's taillights offer access from the exterior, then you'll have an easier time getting to the wiring to allow you to test it for function. It is worth contacting the trailer maker with your VIN to see if they can offer you guidance for accessing the wiring.

You will want to use a tester like # PTW2993 to confirm the signal carrier on each RV taillight wire so that you can match them up by function to the new 4-pole like # HM48030 that you want to add for the second trailer. On a 4-pole the white wire is ground; the brown wire is running lights; the green wire is right stop/turn and the yellow of left stop/turn. Please refer to the linked article.

Towing a trailer behind a trailer is not permitted in all states/provinces so I suggest you first check with the authorities in the areas in which you intend to travel to make sure this practice is allowed.

expert reply by: Adam R