i hook up my sidemarkers to blink with my turning signals.... and my turning signals ONLY turn on when i use them... their not on with the headlights like normal...
Havent taken a look at the wiring yet, since its been snowing.
But on my old Saturn all I did was take the sidemarkers ground, and attach it to the front blinkers power wire. (the fronts had three wires, power-light, power-turn, and ground)
This way when the turn signals turned on it would interupt the ground and shut off the side marker. Which meant they would alternate blinking.