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So I'm having some issues installing aftermarket fog lights I bought off of amazon. I'm almost certain that the relay and/or the switch was wired up incorrectly, so when I try to plug it all into the factory plugs on the car, it does not work. I'm getting power to the switch, but nothing to the lights. I've confirmed that the lights themselves work by hooking them up straight to the battery. So now just to eliminate all said issues, I'm thinking of wiring them up straight to the headlights with a relay so that way it has its own power source, and to eliminate the switch issue. The relay would get power from the headlights, and i would take a direct power lead from the battery to the relay with a fuse of course, which would power the lights. I'm not 100% certain on how relays work but that is my general understanding. What are your thoughts? Would this work?
Here's a wiring diagram I drew up a while ago. I think it'd be safe to assume the relay you're using a a 4-pin relay, and not a 5-pin. Hopefully the numbers on your relay are readable. My experience, those numbers are standard
The 12VDC power in the bottom left (pin 85) is just the switching signal source (e.g. you only want the fog lights on when [car's on/parking lights on/headlights on]), and for that you'd just tap the hot 12VDC line for that. Other side (pin 86), you can connect to any ground. As far as I know, you can switch pin 85 and 86 with no negative consequences since it's just providing power to an electromagnet inside the relay. When energized, it closes the switch between pins 87 and 30, completing the circuit there, allowing power to go from your battery to the fog lights. I'm sure it's safe to assume 30 and 87 can be switched, too. This is just the way I've always wired up relays.
I also drew in a fuse coming in from the battery line (for safety) and a switch coming in from the power sensing line (so you can have more control over the fogs).
Last edited by xRiCeBoYx; Jul 18, 2019 at 02:47 PM.
Connect 2 pins to power: one to ground, one to +12vdc. Hear a click? There's your 85/86 pins. They'll also typically be parallel to each other on opposite ends of the box. 87/30 with be perpendicular to each other
Just an update: I got the lights working with the relay. I didn't add a switch in there, I just connected it to the headlights so that way they come on with the headlights. Thanks for the help guys.
