I have a 2010 f250 XL v10 6 speed 4wd. I was looking into adding factory fog lights to it. I have the factory plug by the headlight. I've read that some XL trucks just need the fog lights, wiring harness for the lights and the headlight switch with the fog light option.

So today my buddy (has an 09 f250 xlt with factory fog lights) and I decided to try his headlight switch in my truck to see if it would send power to the plug by the headlight. Plugged it in, turned the fog lights on and had no power. Actually the little fog light light on the switch didn't light up that I noticed either. So we compared wiring harnesses going to the headlight switch. Both trucks have 9 wires. #21 fuse in the kick panel is intact and good.

Any ideas on what else my truck would need in order to use the factory fog light parts? I know I could run new wiring and use an aftermarket switch but I'd rather it be factory.

Thank you.

 

They may have to be enabled by a dealer in the Smart Junction Box.

I think I recall them being parameter that can be enabled. It is also possible that you didn't sense power at the plug because the fog lights don't exist yet. CAN-BUS vehicles aren't like old switch & relay vehicles. They sense electrical loads to diagnose themselves.

The switch does not control a relay, but it is tied to an input in the main computer. That input will trigger the computer to manipulate outputs. In this case it will close the relay for the fog lights.

If the vehicle doesn't "listen" to that input, you'll get no output. Similarly, if the expected electrical load is not present when the relay is closed, the vehicle has the ability to disable the faulty electronics. The indicator likely will not light up if the computer senses some type of fault (like missing lamps).

2008 was the first year Ford went all out with the CAN-BUS system. There are quite a few differences between 2008 and 2009-2010 programming. It's also entirely possible that the switch you have (2009) is not recognized by the 2008.

 

I going to say my best plan of attack would be to buy the lights, wiring and switch. Install them and see what happens. Then possibly take it to the dealer if it still doesn't work. Its going to have the factory fog lights one way or another.

My local dealer was able to enable my factory trailer brake (my truck didn't come with it). It wouldn't work with just the hard parts installed. So it's a good possibility the fog lights could be enabled the same way.

 

I just installed fog lights on mine. Wired them right to one of my aux switches. Real easy!