It's a whole bunch of wires. Not sure the book breaks that down though.
http://www.google.com/aclk?sa=l&ai=...2.html&rct=j&q=back+off+brake+light+modulatorThx cw...so what happened. I was out the other day sitting at a light. Watching my mirror. This Honda civic comes hauling ass behind me. My instincts was to jump off the bike. Then all of a sudden he he brakes hard and stops close as **** to my bike. It was a dam kid, and notice he was texting on his phone while sitting at the light. Left arrow light came on and the kid bumped me, hit my rear end. Turned the bike off, he got out of the car saying sorry man, sorry man. I fuss his ass out and the only thing he was saying he didn't see my brake light. Pure ******* bad excuse. But make story short. I want to be seen more so I looked at these. A couple of bros of mine have them. I have it ordered. Should get it next week.
http://www.customdynamics.com/brake_hold_module.htm