J-Box - How It Works

Had a look at the Concours wiring diagram (muchas gracias to Guy B. Young for the schematic showing how the J-Box guts relate to the rest of the electrical stuff) and the activities of the headlight relay seem the most interesting. I think I understand it - I just can't believe it.

When you push the starter button, you put +12 onto the STARTER RELAY (J-Box pin 12) which goes clunk and puts +12 onto the STARTER SOLENOID coil (J-Box pin 13) AND the south end of the HEAD LAMP RELAY, which because of the diodes does nothing.

Then the START SOLENOID goes clunk, putting +12 onto the STARTER MOTOR (WHIRR, presumably) AND the north end of the HEAD LAMP RELAY thru DIODE D2. The HEAD LAMP RELAY still does nothing, because both ends are at +12.

Eventually, you release the starter button (VROOM, presumably), the +12 is removed from the START SOLENOID coil (pin 13). Until the START SOLENOID releases, there is still +12 at the north end of the HEAD LAMP RELAY from the STARTER MOTOR voltage, with some low voltage at the south end still connected to the now unactuated START SOLENOID coil. The HEAD LAMP RELAY then goes clunk, and when it clunks, it supplies +12 through DIODE D1 to keep itself clunked, and the HEAD LAMP RELAY coil current continues to flow through the START SOLENOID coil.

A short while later, the STARTER SOLENOID releases, removing +12 from DIODE D2 (pin 10) but it's no longer needed anyway, the HEAD LAMP RELAY keeps itself on through DIODE D1.

If you stall the bike, push the starter button again, the +12 to the START SOLENOID coil causes the HEAD LAMP RELAY to drop out, until it is again triggered by the STARTER MOTOR voltage lasting a bit longer than the START SOLENOID coil voltage.

I like the Concours but this does not seem to be its finest hour.