Stock Fog Lamp Problem
 

I'm in a sticky situation,
I own a 2002 F-150 XLT with factory fog lights. around 2 days ago, I noticed that when I pull the headlamp dial out to turn on my fog lights, they don't come on. I checked the fuses and relay but everything is working in correct order. Also, the indicator light comes on showing that the fog lights are on. I can't seem to figure out why they wont come on. Unless in some odd way both bulbs burned out at the exact same time. If anyone can help me with this problem it would be greatly appreciated.

Indicator icon on the switch shows that fuse #27 in the CJB ( Central Junction Box / cab fuse panel ) is good, and power from the low beam selection on the MFS is good.

The other fuse you checked, was it the BJB ( Battery Junction Box / under hood fuse panel ) fuse #9 - 15A ?

How did you check the relay ?
- This would be pull it, and bench test it with a meter, for continuity, and a 12 V DC power supply to activate the coil.

Did you check for +12 V DC and ground at the fog lamp bulb connector ?
Tan w/ Orange wire = +
Black = ground

Sounds stupid, but do you have you hugh beams on?

the fog light indicator wont light up if the highs are on

SSCULLY- I did check the BJB #9 and it was also good as with CJB #27. My way of checking the relay was to have someone pull the headlight dial out and listen for the click, primitive yes but im not one to understand electrical work. As for the ground and 12V DC, I didnt get a chance to check that yet I just figured if the indicator light comes on and the relay is working the fog lamps should be getting power. I haven't made any modifications to the stock wiring as many do to make the high beams come on with the fog lights still on. I also didnt check to see if maybe in a random occurance both bulbs burned out at the same time.

you really should check the bulbs, there not totally expense, only about 13$(canadian) a piece. i burn through them quite quickly, as i use them as driving lights, and love plowing through snowbanks so i get what i ask for.

its a H10 bulb (it is in my 04), and i can only find them at the stealership.

good luck

Ok, the check of the relay is not really a check, that is a guess at if it is good or not.

To assume that if the Fog icon comes on, on the main headlamp switch, that power should be getting to the fog lamps, is to say you are assuming that the bulbs are burnt out. The icon illumination is from the MFS in the low beam position, and activates the relay. The other half of the relay is how power gets to the fog lamps. Cannot assume anything, at this point.

With too many assumptions and marked as tested OK, without any actual test being done, let us take a base test to see what is going on.

Pull the fog lamp relay, and jumper the contacts. This will test power from BKB fuse #9 to the fog lamps, and eh lamps should illuminate

Don't have which relay it is ( full or half ISO type ), here is both.

https://www.f150online.com/galleries...028-186571.jpg

https://www.f150online.com/galleries...028-186572.jpg

Keep it simple: Check the doggone bulbs FIRST!!

And as sscully mentioned, check fuse #9 under the hood. It should be a 15A fuse.

My money's on the bulbs. The lifespan of modern headlight bulbs is remarkably consistent. They typically burn out within a few hours of each other. If one goes, the other won't be far behind.

-Joe

case closed,
SSCULLY- tried jumping 3 and 5 on the relay and the fogs didnt turn on. I then went with what I should have done in the first place and checked the bulbs. Both were burned out. I still find it very strange that both bulbs would burn out at the exact same time especially when the bulbs were less than 4 months old but hey s**t happens. Just wanted to say thanks to everyone that took the time to help me with my problem especially SSCULLY for the diagrams.

Glad it's back up & runnin, but 2 minutes with a 12V test light or a multimeter before any of this, and you would have known it was the bulbs. Simply unplug the bulb, check the harness for power, and it would have shown power at the connector. Then, check the connector for ground, and it would have shown a good ground. Without even removing the bulb, we would know it was bad.

Removing the bulb, the problem would become obvious too.

-Joe