What are the Wires on My 6 Pin Connector that is on My 2003 Jayco Eagle 14SO Pop-Up Trailer?
Updated 10/27/2025 | Published 03/08/2025
Question:
Hello, I have a 2003 Jayco Eagle 14SO popup trailer. Im currently rewiring the 6 pin square plug. It was wired to a 4 pin connected to a 7 pin adapter. My original wiring on the 6 pin that connects to the trailer has two red wires that have me clueless as to which is which. Any help identifying what to they are for is appreciated. One is a thicker gauge than the other.
asked by: Jeffrey M
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Expert Reply:
Hello Jeffrey,
On your 2003 Jayco Eagle 14SO popup trailer with a 6-pin square connector, the two red wires likely serve different purposes. Generally, a 6-pin plug includes wires for ground, running lights, turn signals, and either trailer brakes or auxiliary power. Since you have two red wires, they’re most likely for the 12V battery charge line and either trailer brakes or interior power. The key difference is the gauge of the wire; the thicker one is probably for charging the battery, while the thinner one could be for brakes or powering interior lights.
To figure out which is which, you can use a Hook Probe Circuit Tester # PTW2993. Start by grounding the tester and probing each red wire. If one wire lights up when the interior lights are turned on, that one powers the inside of your trailer. If one shows 12V when your tow vehicle is running, that’s the charge line for the battery. If your trailer has electric brakes, try probing the thinner red wire while someone activates the brake controller—if the tester lights up, it’s for the brakes.
Another way to check is by applying 12V power to each wire and seeing what turns on inside the trailer. If lights come on, that wire is for interior power. If you hear the trailer brakes click, then that wire controls the brakes. I am sorry that I do not have a more direct answer for you, we do not have a database that supplies us with the schematics on the trailers, plus there is not a real standard. I attached an image of what the functions normally are for the 6 pin connector for you to take a look at as well. Please let me know how it all plays out.
(click to enlarge)
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Kate F.
10/27/2025
Hey Jeffrey, how did things go when you tested those two red wires on your Jayco Eagle with the circuit tester? Were you able to tell which one handled the battery charge and which powered the brakes or lights? Your update could make it easier for others sorting out similar trailer wiring.