good reading on upgrading stock headlight wiring or 9007 conversion

fivespeedsteed

Dirt-Old 20+Year Member
Oct 17, 2003
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Richmond, VA
ive heard that the 9007 bulb is a much better beam than a 9004, and i dont like HID's. i have melted a multifunction switch before from running my lows and fogs all the time so i know something has to be done to the wiring to hold the extra voltage of the 9007. all you do is switch the wires around in the clip i know that. what gauge wire you recommend running.
 
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Ford TSB 89-17-11 says this is caused by overheating in the headlamp circuit. It's a phenomenon affecting '83-'89 Escorts, '83-'87 EXPs and '87-'88 Mustangs. You'll need to replace the headlamp and dimmer switches, several connectors, and then bypass the wiring in the circuit with new 12ga wire run alongside the original harness.
 
Get yourself one of these harnesses to keep your headlight switch from burning up:
http://www.rjminjectiontech.com/products/headlight-harness

Then do this relay modification for your fog lights:
http://www.corral.net/tech/maintenance/foglights.html

Then read this:
http://www.candlepowerinc.com/pdfs/9004_9007.pdf[/quote]

I used the harness from SUV Lighting. Whichever one you use, do yourself a favor and protect the relays from water. I tired gooping them with silicone and that didn't work. I finally wrapped them in a plastic baggie and tied them off with a cable tie - so far so good after a few years of wet weather.
 
good reading. i was always wondering about upgrading the wiring. im not running my fogs. see avatar pic, i like having no fogs, so im not worried about that. i know you have to switch the wires around in the clip for the 9007 to work cause the ground and low and high wires move, but the low beam on a 9007 draws 10 more amps right? i figured that might hurt the wiring. i will do all of that reading and might give this a shot. my friend with an 03 was driving towards me at night and his lights looked great, he had silverstar ultra's and sn95s are 9007 bulbs.
 
The low beam of a 9007 draws 0.83 more amps than the 9004 (assumed at 12V). The last link I provided outlines the reasons not to swap a 9004 bulb for a 9007, but if you must, all you'll need to do it switch some pins around on the car side of the headlight wiring and plug the RJM 9007 harness into it.
 
The reflector in fox body Mustangs is designed to use the 9004 bulbs. The mathematics that govern the distance between the filament and the reflector are precisely calculated for maximum efficiency. Those of you who have studied Calculus in college will understand that the reflector is a parabola with the filament as the central point.
The 9007 use a different filament arrangement that does not match the fox body parabolic reflector, and for this reason, it will produce less effective light, or light that does not align its output to the proper pattern. The modified headlight may direct its light into the eyes of the oncoming driver, off the side of the road or up in the trees above.
 
You will get a noticable difference in light output if you install a 9004 harness like the one from RJM. Your headlights will then be sourcing their power directly from the battery, so they will see the full 14V coming off the alternator. Voltage drop won't be an issue anymore.

You probably don't want to attempt an HID retrofit. It's not a good time.
 
oh i know i dont want to attempt an hid retrofit. so just the rjm harness for a 9004 bulb? is that all i need? does it wire in pretty easy and replace factory wiring or will this wiring run alongside the factory wiring and look ghetto rigged? ill read the install instructions later on.
to avoid starting multiple threads, what kind of light bulbs are we running with good results? i like my silverstars, is there anything better? i know this is a touchy subject so lets avoid this being a silverstar bashing thread.
 
what kind of light bulbs are we running with good results? i like my silverstars, is there anything better? i know this is a touchy subject so lets avoid this being a silverstar bashing thread.
I used Daniel Stern's website as my guide when buying bulbs. Ordered some GE Nighthawks from Amazon. Love them, will absolutely buy them again. They make a huge difference even without retrofitting relays.
 
oh i know i dont want to attempt an hid retrofit. so just the rjm harness for a 9004 bulb? is that all i need? does it wire in pretty easy and replace factory wiring or will this wiring run alongside the factory wiring and look ghetto rigged?

One part of the harness plugs into the driver side 9004 male plug from the stock wiring. The other part gets a ground and 12V from the battery. It just turns the stock plug into a signal wire to tell the relays when to turn on the headlights which now draw their power directly from the battery.
 
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One part of the harness plugs into the driver side 9004 male plug from the stock wiring. The other part gets a ground and 12V from the battery. It just turns the stock plug into a signal wire to tell the relays when to turn on the headlights which now draw their power directly from the battery.
So it will kill my battery if i leave these 9007 bulbs on ? The funny thing is the person who owned this car before me had the 9007's in there. When one blew out, i replaced it with a 9004, and it killed my battery. So now i purchased both the 9007's. I will have to wait to see if it starts withing the next few days. Although, he upgraded the stock headlights to a one piece headlight piece. I hope he did the conversion right, or i will find out the hard way.
 
I interested in this headlight thing, I am leaning towards the one piece lights. But I'm not going to hack any wires to do it.
Its actually just switching one wire with one other, seems pretty simple from what i saw on the diagram. I hope to have no issues, but will update if i do. So far, i think i found what was causing my battery to die, and it wasn't the headlights. It was the dam mirror on the sunvisor. I saw it on when i entered my garage at night. Gave it a good slap, and it turned off.