relay, fog lights, headlights

Hi, I have hooked up my RV fog light as DRL, using a regualr relay that when the ignition is on the fog lights are on too. But I want to disable the fog lights when the normal headlights are on. So a relay the will interrupt versus create a connection when the power is applied to the relay. What should I be looking for? Gary

Instead of grounding the relay's coil, connect it to the headlight +12V switched supply. Provided the (headlight) resistance is low enough, the relay will energise thru the lights when off. No problem with old lamps. (HIDs might be different...)

hi, you'll need a SPST normally closed relay, or SPDT relay...a bosch type relay will be fine. wire as follows: terminal 86 to headlight switch, headlight output...has power when headlights are on. terminal 85 to ground. terminal 30 and terminal 87a will be used interrupt the ignition feed or ground of your DRL/fog light relay. you can remove the ground from the DRL relay and connect to terminal 30, then connect a wire to connect terminal 87a to the ground side of the DRL relay....terminals 30 and 87a are interchangeable in this application. mark

Very cool - I will give that a try. Any thoughts or ideas on where to get the relay. I am in San Diego and most people give me the confused look when I ask about relays :-)

relay...car audio shop, best buy, radio shack, auto parts store, fry's?

But you already have the relay.... !?!

@oldspark Yes - I will try your suggestion first as the headlights are HID's The other suggestion will be my next step.