Question on brake wiring

[pnedac]

83 XS. PO was a tool and completely had this bike out of whack. Now as I am almost done with the rewire I am wondering why there are only two wires out of the brake light. This is an aftemarket light that was attached and does not appear to be a motorcycle light. Shouldn't there be three wires? One for running, one for brake, one for ground? As this is an abnormal situation the manual is not helpful in gettinghtis sucker working right. Any help is appreciate.

Thanks!

Pnedac

 

[RFLIVES]

Ground to the body of the lamp. one wire for running light one for the brake light. Most sparto lamps are like this

 

[jayel]

older Harleys and English bikes used frame grounding, wasn't until the japanese bikes came along that they started using a dedicated ground wire, much better system