Okay, I put in new switches, have a relay system all ready to go to turn on my neon underbody and interior neons... but I want to have them turn on only with the headlights (just like how the fog lights do)... but I am having one problem... every connection to the lights and the fog lights are always reading 12v, even when the lights arent on. I even went straight to the headlight harness. I dont think I screwed up, but with my multimeter to the 3 wires going to the head lights, and the ground of my multimeter to the body of the car, it comes up 12v... EVEN with the lights off... This is very confusing to me! I went to the headlight fuse, and it is always hot 12v also. anyone know how I can accomplish this?

 

I am no expert at this, but the first thing I would do is check your headlight leads again and check them when the lights are on to see what changes, because theoretically if all leads into your headlights are hot, your lights should be on all the time.

 

I did some more testing.. and found this... Yes, the lights are "hot" all the time, showing 12 volts... but when the lights are on, there is no negitave voltage... so the negative turns on and completes the circuit... but the problem is, I HAVE NO IDEA where the switched negative is, other then the harness going to the lights... the fuse is always hot... so fuse taps are useless.

 

Well a cheater alternative would be to tap into the parking light circuit, same effect and hardly anyone I know ever runs with just the parking lights on for to long .. That will at least save you some headache ..

 

any green wire on the car is headlight/running light. use that for the trigger on your relay.

 

Use the switched (-) out of the headlight, either headlight. It should be a Black wire with White stripe (this is for low beam). High beam is the Black with Yellow stripe. Use that to ground your neon light relay to energize it. I used this method for my driving lights so they will only come on if I turn the switch on & the headlights are in the "highbeam" position. If I switch to low beams, the driving lights drop out along with the high beam, as California law requires....