What Wire Do You Hook Electric Trailer Brakes To On Trailer Where Brakes Were Never Connected?

Question:

I just noticed when I got my trailer two years ago the break wires were never connected and but everything else works from the running lights to the hydraulic lift on the dump. I see a green wire coming from the break and a brown wire that goes through the axel. My question is which wire do I connect to the running wire that goes through the whole system?

asked by: Eric C

Expert Reply:

Hey Eric,

On your brakes you'll have 2 wires going to each brake magnet. You need to ground one of the wires (doesn't matter which one), and use butt connectors like # DW05745-10 to connect the other wire to the brake output wire on your trailer.

Now I don't know what wire color that'll be on your trailer, as each trailer manufacturer uses whatever wire color they have on hand (never seems to be a standard, though it should be blue in a perfect world). You'll need to either trace the wire back to your junction box and see which wire gets hooked up to the brake output wire coming from your trailer brake controller, or you can use a circuit tester like # PTW2993 to test each wire to see which gets power only when you apply the manual override on your brake controller. This should be a larger wire (12 or 10 gauge) not the smaller 14 or 16 gauge wires your light circuits use.

expert reply by: Samuel C