so all i need to do is connect the wire to a switched power source and it should work?

 

If you followed the instructions and If you have wired and grounded and fused everything correctly. Then yes, it's a possible maybe.

 

ROFL... What he meant was; "In theory".

 

I don't know what year blazer you are working on but on my 99 BlaZeR2 ,I mounted the relay to the front of the under hood fuse box.There is a hot post on the outside of it for 12v.I put an inline fuse between the relay and the post. I only ran one wire to the interior.
This was for the switch. I wired mine into the factory headlight switch.This way I could leave the fog light switch in the ON position and they could automatically turn on/off with the headlights(NON DRLs on 99s)Otherwise for the fog lights to come on I have to manually turn on the parking/headlights.This way if I try to get out of the BlaZeR2 with the lights turned on,it will warn me. I have seen alot of my buddies wire up the fog lights to operate solo and they forget to turn them off and it's hello dead battery!

 

If you wire up the switch (to activate the relay) to a switched ignition source under the dash, you can never leave the lights on and they