I'm replacing the worn out plug on my trailer towing light harness. It's a Lite Mate (Hopkins?) that was on the truck when I bought it used. Looks like the plug and play harness that plugs into the tailights.
My question is: This is a four flat plug...I want to solder a generic four flat to the existing wires where I cut the old one off. Problem is, the Lite Mate has five wires going into it. The generic has four going into it. The Lite Mate plug has stamped on it's casing which wire is what; running lights, brake lights, left turn and right turn. The plug casing is worn where the 5th wire(blue) is named, so I don't know it's purpose. Without having tried it yet, can I solder the four to the new plug leaving the blue wire unused? Or is this a ground of some sorts, and needs to be tied in with another wire? I hope my question is making sense.
I know I can get a new Hopkins harness for about $25. But I was hoping to go the cheap route as I'm unemployed. Thanks in advance for any info.