Bonneville America Forums Forums Technical Forums General Tech help on wiring in afthermarket taillight

I bought a new taillight and it has 3 wires and the original harness has 2 wires. How do you wire that up right without messing anything up?

I would guess that the third (new)wire is the ground. You have the positive for the clearance lights and one for the break but you need to have the gound in there somewhere and I think that the original got its ground from the fender

Daniel,

I agree with Evanman. The third wire is most likely a ground wire. It may be redundant if your new turn signals are all metal & they bolt into the metal fender. If not, hook it up somewhere that is inconspicuous.

-BT

Like they said. The black is ground, the other two wires are for the running light and the brake light.

What bike are you working on...I had exactly the opposite problem on my 03 Speedmaster. The new light only had two wires while my harness had three. I ended up running the black ground to a screw inside the light housing and the other two are obviously for the two wires coming from the bulb socket.

The bike should have three wires to the rear light - black for earth, blue for brakes and red for taillight. If the light fitting you've bought only has two wires chances are they're for brake and taillight - connect the black earth wire to the body of the light fitting to ensure a decent earth.

Matt

I was looking at the turn signal wires i guess , because when I cut the wiring i discovered that the original harness did have 3 wires. I feel like a big dummy now. I didn't look close enough or was in a big hurry at the time. Anyway, thanks for the help everyone. I should just stick to painting evidently. I should have the bike rollin' out in a couple of days so look for my pics and let me know what ya think.