Electrical 2003 Mach 1 Headlight switch

[Sketchy_GT]

Hello, I have an 03 Mach 1 and I’ve just recently started having an issue with the headlight switch. When it first started I noticed the gauge cluster lights weren’t on as well as the fog lamps, but everything else worked headlights taillights etc.. then two nights ago I noticed the taillights had quit. So yesterday I went to buy a new headlight switch as I noticed I could put it in just the right spot and get it to work everything. So when I got the switch out the connector seemed burned some so I was sure it needed replaced too. So I bought the connector today and installed both and still nothing. So I checked fuses and the park lamp fuse in the under hood fuse box was blown. So I thought sweet the short that burnt the connector blew that fuse so I replaced it and everything seemed to work after that. I tested it a few times and it all seemed good... right up until I had to turn my lights on when it started raining this afternoon. That’s when I noticed the gauge lights weren’t on after a few minutes. And I then thought I might have smelled something, but that could just be me being paranoid. I pulled the bezel out and took the switch back loose and nothing seemed burnt or out of place in there but the fuse blew again. I did notice even with the fuse blown I could put the headlight switch in just the right spot to get it to work the gauge lights at least, so I’m real confused on what to do next.... Please Help

 

[wmburns]

It would help the trouble shooting if we knew WHICH fuse is blowing. Use the Ford fuse numbering system so that I can look it up on a wiring diagram.

1999-2004 BJB CJB fuse panel layout:
https://www.allfordmustangs.com/for...r-swap-wont-fire-please-help.html#post2669271

 

[Sketchy_GT]

It would help the trouble shooting if we knew WHICH fuse is blowing. Use the Ford fuse numbering system so that I can look it up on a wiring diagram.

1999-2004 BJB CJB fuse panel layout:
https://www.allfordmustangs.com/for...r-swap-wont-fire-please-help.html#post2669271

Okay sorry about that the one that keeps blowing is the park lamps fuse in bjb I think F1:10 is the exact location if I looked at the right diagram

Fuse J is the one in this image here

 

[wmburns]

Finding a short to ground can be a challenge. If this were my car:

• Perform a through visual inspection of all of the exterior light sockets. Look for evidence of water damage or corrosion.
• Inspect the visible parts of the body wiring harness. Look for obvious physical damage.

Warning. Advanced electrical trouble shooting follows. Take out the fuse that is blowing and jump the fuse with a test light. Turn the parking lights on. Does the test light light? Is it bright or dim?

Now removed the exterior light bulbs one at a time and note what the test light does. IF the test light still lights up with all of the bulbs removed then this "proves" there's a ground fault somewhere in the circuit. Now it's a matter of performing a "wiggle" test on the wiring harness until you see the test light's brightness change.

 

[Sketchy_GT]

Okay guys I did the test light test and showed no shorts in the system started tracing the wiring diagram and turns out that when I unplug the taillights from the body harness everything else works as normal... it is a sequential kit so that may be what I’m after but I’m going to test all the bulbs first more details to come

 

[wmburns]

If this were my car I would CONFIRM that the tail lights were actually grounded with a real ground that is able to carry current.

I have seen this sort of thing happen when the tail lights are NOT grounded. This causes the stop lights and the parking lights to back feed in series through each other.

 

[Sketchy_GT]

Alright guys I didn’t get to take a picture but when I pulled the right taillight I discovered some burned wires which I found out happened because when the sequential kit was installed one of the wires got behind the bolt and was tightened against the car which obviously over the course of time tubes a hole in it grounded it out and burnt the wires causing my short. Thank you for all your help