When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The rear brake switch is bad. This is a common problem and is an easy fix. I'm not sure where the switch is on your bike but it's usually on the right side of the lower frame.
Have you recently changed the throttle grip or had the front brake lever off the bike? Common prob is that you need to watch the brake switch on the front lever. The little button snaps off easily.... result is, you need a new switch at the lever.
One quick way to check is to disconnect the rear brake switch on the right rear side of the frame. If it you turn on the bike and the brake lights are still on, then it's your front brake switch. Had this happen to me. Hope this helps.