Brake Bulb Warning RD350

[doggone1]

Hi all dont know if this is the place to ask but ill explain what im trying to do my rd 350 has a light on the dash that lights up when the brakes are applied and if the brake light bulb fails it flashes.
As far as I can see, the yellow to the back light has two functions (apart from actually supplying the plus for the brake light bulb).
When brake light bulb OK, yellow "plus" applied via brake switches causes lamp checker internals to switch "earth" for indicator light on (ind. light plus comes from G/W).
When brake light bulb "blown", earth circuit from lamp checker to back light (also via yellow) broken, causes lamp checker to switch (via internal timer) "earth" to flash indicator light.
Is a strange circuit. It must be a comparator, it"s using the green wire from clock bulb to compare the voltage with the yellow to the brake light probably using a delay (capacitors), if it sees a lower voltage appear on the yellow, which it will when the brake light operates due to volt drop caused by the 21watt load, it turns on the red clock light, if it sees the same voltage appear on the yellow, i.e. bulb blown, it flashes the red light. Be a few transistors, capacitors etc in there to make up logic gates.
I am missing the part that operates it and wondering if I could make one

 

[dr pepper]

Do you remember the 350 powervalve?, scared the heck out of me when I was 17.

I probably wouldnt get involved in the bikes circuitry too much, I'd probably do something like sensing the voltage on the switched brake circuit, and at the same time sense the current with a reed switch with the wire that carries the current to the bulb wrapped around it, then have a simple transistor to switch on the led if there is voltage and no current on the switched + for the brake bulb, if you want it flashing you could use a 555 and have the circuit control the reset i/p.

 

[doggone1]

Remember them well bikes with a power band always make you smile