Fog Lights Not Turning Off

[ToddEichel]

Hi all, got a problem with my fog lights not turning off. 1998 XLT AWD/4WD 4.0L SOHC, factory fog lights. Normally the fog lights turn off when the headlights turn off, but yesterday after stopping at a shop for a couple minutes, saw my fog lights still on when I got back to my truck. Started the truck, headlights still off (daytime, just raining, so auto headlights weren't a factor) but fog lights still on. Hit the button to turn off the foglights, they stayed on. After messing with it for 5 minutes while driving away, they eventually turned off and started acting normally again. got to work this morning, same thing, turned the lights off then the truck off and they stayed on. Left it for 45 minutes, no luck. Tried pulling the fuse that, according to the owners manual, is for the right headlight and fog light relay, and they still stayed on. Eventually unplugged the wires from the backs of the bulbs, but the light is still on, on the fog light button, so I know there's still power going to them. Obviously I don't want to leave the wires hanging, just don't want to kill my battery. Anyone have any ideas where the problem might be?

 

[Billy177]

sounds like a bad relay

 

[DeRocha]

Welcome to the site... The relay could be sticking ON causing as indicated by Billy177. But the lights will go off if you pulled the fuse. Can you locate the 12v relay which controls the fogs and take it out? I don't know the exact location on your model, but it may be located in the power distribution box under the hood.

 

[Billy177]

i think it is loated in small relay box by the air cleaner

 

[ToddEichel]

thanks, guys, I'll take a look there and get back to you. When I went back out at lunch they were off. Plugged the wires back in and they worked normally. Played with it a little later while I was driving around and they were staying on, then started working correctly again. I hate intermittant problems.... grrr....

 

[ToddEichel]

All righty, the fog lights are controlled by a 15 Amp mini-fuse on the fuse and relay block under the hood on the right hand side towards the back (between the battery and firewall). Unfortunately everything seems to be working fine now, no idea what the problem was (is....) but at least the fuse under the hood controls only the fog lights (and DRL's, which I don't have) unlike the fuse inside the cabin that also controls the right headlight, so if they stay on, I can at least pull the fuse and not drain my battery. I hate not knowing what the problem was/is...

 

[DeRocha]

Todd did you find the 12v relay for the fogs and are you familiar with how relays work (If not I will post a diagram with write up). Basically the toggle switch in the dash is used to magnetically activate the coild with the relay which in turn connects the fogs to the battery... If the relay goes bad the switch will not work and the connection can get stuck on or off (On in your case).

 

[ToddEichel]

No, didn't find the relay for the fog lights. There wasn't a relay for the fog lights in the box with the rest of the relays in the back driver side of the engine bay, just a 15 amp mini-fuse for them (according to the diagram and lables in the owners manual, anyway). My Haynes book doesn't show where the relay is for the fog lights, either. I did some reading and understand how the relays work and that definitely makes sense that the relay is sticking in the on position some of the time. Can you tell me where else I might look? There isn't anything on the passenger side near the airbox, like was suggested in a previous post...

 

[DeRocha]

You can either have a helper toggle the fogs on/off while you listen for the relay to click. Otherwise you can try tracing the hot wire from the fogs back to see where it goes.