led parking light flash, how to?

HI

I would like to find out how to wire existing led body markers on my tow truck to flash when a switch is turned on and work as parking lights when the switch is off and parking lights are on @ night. I bought an led flasher from Whelen engenering that has a red wire, a black wire, and two output wires ,left and right side and a pattern select wire.    The exsisting leds are mounted on the side of the pylon (lightbar rack) behind the cab of my tow truck . I would like to turn them into warning lights with the flip of a switch and retain the parking light ability when they are off. Would I do this by flashing the ground?  in this case i would have to change the polarity of the output of the flasher with a relay ...right?  thanks for any help or diagrams....Leon

first, remove the current parking light feed connected to the LED lights. use a standard relay. connect term 85 to ground, term 86 to the 12v power feed that comes out of your rocker or toggle switch. connect term 30 to the parking light circuit in the truck, connect term 87a to your LED markers, connect 87 to the red wire on your flasher, connect the left and right side outs of the flasher to the LED lights, connect the black wire from the flasher to ground.

Thnk you sir!!!

Will this work when parking lights are off and when they are on? 

thanks,   Leon