Electrical Issues with Lights

[Windy_3V]

I’ve been having various lighting issues with my ‘07 3 valve for a while now. My passenger side headlight has been out for a while and I haven’t figured out why. However, if I turn my high beams on it works just fine. So far I’ve replaced the bulb, both connectors going to the headlight, re-soldered the wiring, and replaced both low and high beam relays and neither fixed the issue. None of the fuses are blown either which wouldn’t make any sense anyways since the drivers side works fine.

Recently I noticed now my passenger side brake light doesn’t come on either and only comes on if I have my parking lights or normal headlights on. My third brake light and fog lights have gone out too but they’re kind of old and probably just the bulbs but I haven’t bothered trying to replace them either since they could have the same issue as well.

I’ve read that the SJB can be an issue on these cars but I don’t know much about it besides the fact that you can’t get them anymore and if they’re damaged you’re only options are to get it repaired or try to clean it up yourself. Also I’m not sure where it’s located but from what I’ve read it’s under the fuse box in the engine bay?

Also it’s worth mentioning I have aftermarket headlights and taillights (Raxiom DRL Projector with LED bulbs and Raxiom Gen 5 respectively) and didn’t have any issues when I first installed them which was years ago.

I’m running out of ideas so I’m thinking it has something to do with the SJB but I wanted to get a second opinion before I do something stupid and fry all the electrical in my car lol! Any help is appreciated!

 

[MrBhp]

SJB is located inside the car, passenger side kick panel. If you have not cleaned your cowl drains you need to start there. Water intrusion could be the problem. There is a thread on here with some detail on the process, along with other sources of water intrusion. It's a good place to start.

 

[MrBhp]

2005 - 2009 Water Leak Repairs.pdf

drive.google.com

 

[Windy_3V]

Cowl drains are new to me I haven’t even heard of that. I live in Florida and the car has been through some pretty nasty storms so I wouldn’t be surprised if water intrusion is the issue. I’ll definitely give that thread a read and see if that helps. Thanks for the tip!

 

[Autokyrios]

Water was an issue for some SN197 cars but not everyone (I never had a drop of leak issue). However the drain nipples in the firewall are very prone to collecting cr*p and clogging up, even just with heavy pollen, and the door drains should be checked regularly, too. Really you shouldn't have an issue with door water if your window seal is good. Usually stuff comes in from the fender well through the lower firewall passthroughs, but again as long as they're in good order and pliable they're fine. Don't run through any high water (but that's a given).

What I HAVE seen for the passenger SJB with water is actually condensation from the AC if it's not draining properly or you have a habit of running it on high in a very humid place.

It's pretty easy to check, though. Just be careful as much of the safety equipment stuff has a fuse through there and you don't want to probe that stuff (unless you like surprises).

A quick run through all your fuses would be a good idea (pull them out and flashlight check them, don't just look at them). Relays can be tricky to test and personally if I have a hair of a doubt I just replace it (sometimes expensive but figure how much aggravation you've already spent...brain cells are more valuable).

Unfortunately, when the electrical gremlins come out, sometimes the only way to chase them down is wire by wire.

Ford Workshop Service & Repair Manuals - fordrepair.info - 2005 Mustang 2005 Mustang Headlamps. autolamps

Ford Workshop Service and Repair Manuals, 2005 Mustang Wiring Diagrams Headlamps. Autolamps

iihs.net

Ford Workshop Service & Repair Manuals - fordrepair.info - 2005 Mustang 2005 Mustang Turn signal, stop, hazard lamps

Ford Workshop Service and Repair Manuals, 2005 Mustang Wiring Diagrams Turn Signal, Stop, Hazard Lamps

iihs.net

Ford Workshop Service & Repair Manuals - fordrepair.info - 2005 Mustang 2005 Mustang Reversing lamps

Ford Workshop Service and Repair Manuals, 2005 Mustang Wiring Diagrams Reversing Lamps

iihs.net

 

[Windy_3V]

Water was an issue for some SN197 cars but not everyone (I never had a drop of leak issue). However the drain nipples in the firewall are very prone to collecting cr*p and clogging up, even just with heavy pollen, and the door drains should be checked regularly, too. Really you shouldn't have an issue with door water if your window seal is good. Usually stuff comes in from the fender well through the lower firewall passthroughs, but again as long as they're in good order and pliable they're fine. Don't run through any high water (but that's a given).

What I HAVE seen for the passenger SJB with water is actually condensation from the AC if it's not draining properly or you have a habit of running it on high in a very humid place.

It's pretty easy to check, though. Just be careful as much of the safety equipment stuff has a fuse through there and you don't want to probe that stuff (unless you like surprises).

A quick run through all your fuses would be a good idea (pull them out and flashlight check them, don't just look at them). Relays can be tricky to test and personally if I have a hair of a doubt I just replace it (sometimes expensive but figure how much aggravation you've already spent...brain cells are more valuable).

Unfortunately, when the electrical gremlins come out, sometimes the only way to chase them down is wire by wire.

Ford Workshop Service & Repair Manuals - fordrepair.info - 2005 Mustang 2005 Mustang Headlamps. autolamps

Ford Workshop Service and Repair Manuals, 2005 Mustang Wiring Diagrams Headlamps. Autolamps

iihs.net

Ford Workshop Service & Repair Manuals - fordrepair.info - 2005 Mustang 2005 Mustang Turn signal, stop, hazard lamps

Ford Workshop Service and Repair Manuals, 2005 Mustang Wiring Diagrams Turn Signal, Stop, Hazard Lamps

iihs.net

Ford Workshop Service & Repair Manuals - fordrepair.info - 2005 Mustang 2005 Mustang Reversing lamps

Ford Workshop Service and Repair Manuals, 2005 Mustang Wiring Diagrams Reversing Lamps

iihs.net

All very true. I don’t have any obvious leaks. In the 2 years that I’ve owned the car I’ve only found water in the car once after a really bad tropical storm but I had some of these issues before that. Additionally, I hardly use my AC as I prefer to roll my windows down but I do occasionally use it. I don’t think I’ve ever put it on full blast lol. Thanks for the input and especially for the wiring diagrams those are really helpful.

 

[DieHarder]

I'd say the most direct way to troubleshoot this is use a test light/VOM and check for 12vdc/gnd at the plugs. If you have it, great. If not, chase the circuit and determine why. I've had shorts/opens and breaks in wiring. Usually, not too difficult to determine the problem/source but chasing down test locations can be tedious.

Here's some Diag/Testing for the headlights on 2005 - 2010's. I think a lot of people go right to the wiring diagrams and miss the fact that there's a lot of extra information in the "workshop manuals" section including electrical that explain how those circuits work and troubleshooting procedures (Pinpoint Tests). Hope this helps. Good luck.

Ford Workshop Service & Repair Manuals - fordrepair.info - 2005 Mustang Exterior Lighting Headlamps

Ford Workshop Service and Repair Manuals, 2005 Mustang Workshop Manuals Electrical Lighting Exterior Lighting DIAGNOSIS AND TESTING Headlamps

iihs.net