Wiring headlights and fog lights together

gcjabecker · Jul 17, 2015

I'm sure this has been asked, but I couldn't find anything specific.

Got a good deal on some Custom Accessories HID lights (they get good reviews, and I think they are discontinued - If anyone is intereste, and if anyone has any Ollie's Discount Warehouses by them, I think they bought the inventory - $19 for 4" and $30 for the 7") but I digress:

Anyway was going to wire them to the fog lights with appropriate fuses, but was shocked to find that many states, including Maryland don't allow more than 4 lights.

Next option was to wire new switch to one of the blank switches in the factory panel, but there is ample information on why this is difficult / impossible (circuit board running full length of panel) and don't really want to add new switch panel for only one switch.

So after my rambling introduction, here is my question:
1. Can I wire my headlights and factory fog lights together to run of the main headlight switch. I understand fogs will always be on when heads are on, but I almost always use them simultaneously anyway.
2. Then hook up my new HID's to the factor fog lighting, so they are only activated when I hit the factory fog switch?

Seems relatively simple, but I'm sure I'm missing something.

Thanks for any advice.

Pedals2Paddles · Jul 17, 2015

Well what year model Jeep do you have? The wiring and control systems are all different. You CAN do what you're asking. It's the HOW that will differ by model.

gcjabecker · Jul 17, 2015

Sorry, should have put in this info:

2011 2 door sport.

Pedals2Paddles · Jul 17, 2015

OK. So you cannot direct wire this stuff together due to the electronic systems controlling the lights. You will need to use your headlight circuit to drive a relay, and you will need a 6000uf capacitor in parallel at the relay coil to smooth the PWM signal that is on the headlight circuit. Use that relay to switch on whatever lights you want, in your case, the stock fogs.

You can wire the stock fog circuit into the HID ballasts directly for you new lights. I don't think there is PWM on the 2011 fog light circuit. If the ballasts don't fire properly, you will need to use a relay on the factory fog light circuit in the same manner I described above.

Honestly, I think you're better off just installing a switch for your new lights and leaving the factory system unchanged. It would be remarkably easier.

gcjabecker · Jul 20, 2015

Pedals:

Thanks for the awesome and detailed reply.

Bought the bullet and purchased external switch and panel and will install this weekend.

Thanks again

Pedals2Paddles · Jul 20, 2015

You're welcome. You'll be happy you did.

Wiring headlights and fog lights together

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