alternating lights on a stop sign

Hi everyone,

Ive got an old school bus stop sign kickin around and some parts that need to be used.

heres my question, i have an electronic flasher but cant seem to get it to flash. i think im wiring it wrong but i dont know, and i want to wire it up with a relay so that i can flip a switch and have the lights alternate back and forth. The bottom of the flasher looks like this, but there are no terminal markings on the bottom of the flasher unit so this is where i get lost. please help !!!

another way would be to use a relay and regular flasher.

BUT HERE IS THE WIRING:

LEFT Terminal-Light #1-Positive Output

MIDDLE Terminal-12 Volt Positive Input

Right Terminal-Light #2-Positive Output

test this with a test light 1st. im not sure what flasher model # u have so i cant be totally sure, but this is the way many are online. PS SOME ARE 6 VOLT NOT 12 VOLT IN/OUTPUT FLASHERS!!!