Electrical Fog lights come on with headlights

sav22rem22

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Feb 6, 2020
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So I recently tackled the project of re doing all the wires behind my headlight switch on my 89 GT. It’s always had weird affects on my car like the headlights seem to pull a crazy amount of power and my fog lights turn on when the headlights are turned on.

Upon taking the switch out I saw that there was nothing plugged into the fog light switch at all. I did also see that the Blue/Black wire and the Tan colored wire were just wrapped together. So I ordered a new headlight switch and fog light switch harness and switch. The picture above is what the current wiring looked like which is why I didn’t feel bad about re doing all of it. It was a mess. So after i finally got everything done and made sure to do it all right I wired up the fog light switch correctly and it still does nothing and the fog lights still come on even though they aren’t wrapped together anymore.

What could be causing this? I really suck at wiring and have next to no knowledge on anything wiring. So I’m really lost and confused and a little irritated that I spent all that time and money rewiring it just for it to not work. Any help is greatly appreciated. Here are a few more pictures of before and after the job below. I know my work doesn’t look the best but it’s my literal first time ever doing anything like this.
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Mustang5L5

i'm familiar with penetration
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Feb 18, 2001
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Sounds like a wire is still crossed somewhere. Double check the wire layout against this diagram, bottom right.

3C909AB5-D02D-4DAC-A1F6-4EC7037A8867.jpeg


might want to replace that melted connector.

You might actually want to split off the fog lights and wore the independently. They are know to overload the wiring and cause fires, or melted connectors as you can see. Googke 87-93 mustang fog light fix.

 

sav22rem22

Member
Feb 6, 2020
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North Carolina
Sounds like a wire is still crossed somewhere. Double check the wire layout against this diagram, bottom right.

3C909AB5-D02D-4DAC-A1F6-4EC7037A8867.jpeg


might want to replace that melted connector.

You might actually want to split off the fog lights and wore the independently. They are know to overload the wiring and cause fires, or melted connectors as you can see. Googke 87-93 mustang fog light fix.

Greatly appreciated on the diagrams. I’ll get to looking as soon as possible. Yeah I don’t know why I forgot the picture but I did actually replace the connector and properly redid all the wires including the tied together fog light wires. Once again thanks so much for the diagrams
 

sav22rem22

Member
Feb 6, 2020
60
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North Carolina
Wow, that was a fire waiting to happen. Glad you got it repaired, someone jury rigged that wiring :nonono:
Yep. I went for over a year without seeing any of that and I’m so thankful it didn’t burn me or my car to the ground. Unfortunately my whole car is sort of rigged together from the previous owners and I’ve been spending all my time fixing their mistakes rather than enjoying the car
 

DemonGT

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When using my headlights and fog lights it would over load and shut off my headlights and fogs. Common issue, someone
on here or corral had a how to wrote up with a parts list to get from your hardware store and how to rewire the fogs to not over load the circuit. Someone may have it saved and could post it.
 

General karthief

wonder how much it would cost to ship you a pair
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Look for post #11 I think
 

sav22rem22

Member
Feb 6, 2020
60
4
18
19
North Carolina
Sounds like a wire is still crossed somewhere. Double check the wire layout against this diagram, bottom right.

3C909AB5-D02D-4DAC-A1F6-4EC7037A8867.jpeg


might want to replace that melted connector.

You might actually want to split off the fog lights and wore the independently. They are know to overload the wiring and cause fires, or melted connectors as you can see. Googke 87-93 mustang fog light fix.

Yeah I’m going to look tomorrow and try to find where the wires are crossed. My fog light switch does nothing and the fog lights come on when the headlights are turned on. So once I figure that out I’ll do the fix to put them on a different circuit. Is the fix you linked me the same one I saw jrichker post about on here a while ago? If I remember right that is
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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Massachusetts
Probsbly so. If you just search “fog light fix” it should pop up.

if you look at the wiring diagram, Ford wired the headlights and fog lights all through one single terminal on the headlight switch. As you’ve seen, this is not good
 

90sickfox

Wasn't a pretty sight...and I've got big hands
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Check the wiring up front. They may have wired the fog lights to the headlights at the front of the car.
 
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