Fog lights won't work

[jtexplorer]

Hey everyone, I recently picked up a 2010 Explorer XLT V6. I honestly didn't even realize it had fog lights until I was changing the oil yesterday. But it really didn't make a difference when I realized I had them, because they don't work anyway.

I am good with electronics, and I think I have the issue traced back to the headlight switch, but I don't have diagrams available. So much of newer vehicles are computer-controlled that I would appreciate any first-hand experience with my problem.

Here's how my troubleshooting has gone so far:

-I put an ohmmeter across the fuse, and it is good.

-I jumped (bypassed) the relay, and the fogs turned on, so I know the bulbs are good and the wiring between the lights and the relay is all good.

-I put an ohmmeter across the normally open relay terminals as I applied power to the relay's coil terminals, and the relay activated and closed the terminals, so I know the relay is good.

-I took the headlight switch out of the dash and, using an ohmmeter, I was able to find the pin used to control the relay. I used an ohmmeter between the hot pin and the fog relay pin as I cycled the switch, and there was no change whether the switch was engaged or not. This led me to blame the switch. However, when I jumpered between the hot pin of the connector and the fog relay pin, nothing happened. I have no idea why. I think that putting 12v to the wire leading to the relay should cause the fogs to turn on. I tested resistance between the negative side of the relay coil and the negative battery post, and it showed good connectivity. I did have the headlight fuses pulled so I didn't drain my battery as I was troubleshooting. Could this have caused the foglights to not work somehow?

Tell me what I'm missing! I'm inclined to buy a new switch because it is not too expensive, and the switch is the only component in the circuit that I was unable to verify as good.

Thanks in advance for any help.
- Joe

 

[ronwc]

Not trying to be a smartass or anything, but you do realize that you have to turn the headlights on first then pull switch out to turn on foglights.

 

[jtexplorer]

Yes I knew the headlights have to be on in low beams.

What I didn't realize is that the engine has to be running. I feel like a moron, but at least my issue is resolved.

Feel free to delete thread, unless you think my troubleshooting procedure could be beneficial.

- Joe

 

[JeepGuy25]

Haha dude dont feel bad. When I first bought my explorer I took it straight from the Tag place to get inspection for my state. When it was idling during the emissions check, I noticed one of the fogs was burned out. While it was on the lift, I went to take the bulb out, and saw that the plug was off, and some wiring modifications were done. So I plugged it in, went to the switch and turned them on, nothing. Neither side worked. Then I thought I blew something out by plugging the light back in due to the hacked wiring.

Later I realized that when I tried them the second time the key was off haha. Its kind of set up weird that way. Huge relief when I realized I didnt have to chase wiring gremlins haha.

J.