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Headlight Wiring Harness

new 4/05/2004, updated 06/27/2004, updated August 7, 2011

August 7, 2011 - How to build your own Headlight Wiring Harness

I did this a long time ago, its pretty basic compared to what I do now.
use wire sizes as you like, I used 14awg for anything that would carry power for all bulbs at once. 16 for individual sides. 18 for the control, which is bigger than you need but smaller than 18 starts to get hard to work with.
the diode in the diagram there is optional, it allows the low beam filaments to remain on while the high beams are on, so when you turn on the high beams you get all 4 on at once. its a nice improvement in light! if you do this make sure you use larger wire such as 14 like I used) for the ground from each of the bulb sockets, since with both filaments on at once the current for both passes through the same ground.
I did the same thing on my Corvette but added a switch in that circuit so I could control from inside if I wanted 4 on at once or not. but that car has separate high and low beam bulbs
I also apparently didn't write down what colors the stock harness wires are. the ground is black. the other two are blue/white and tan/white if I remember correctly. you'll have to test quickly with a meter to find out which is high and which is low.
also as you can see from the drawing I added aftermarket sockets with larger wire and left the stock sockets wrapped in tape and not used. the whole thing is fairly simple! with mine I didn't mount the relays either, I just wrapped them up so they would be water tight (actually put them in big tubes of heat-shrink) and tied them to something with wire ties, they sat behind the driver's side headlight area. 

good luck, let me know if something isn't clear!

97 ES
10 TBM


Does anyone have any information on how to install the upgrade wiring harness for the headlights.

Thanks Danny NYC.

You plug your left headlight into the harness male plug. Find a ground on the left fender for the relays. Use the backmost post on the passenger side of the engine compartment fuse box of the two relay hot wires. Use the screw under the headlight and to the inside for the headlight ground. Absolute best headlight ground would be back to the battery of to one of the major ground points on the frame where other grounds are located. Plug in headlights.

Paul Nimz

Pretty easy.

Dan Carman


It should also be noted that you probably will want to re-aim your lights. Ford has a tendency to aim them low.

Here are just a few links to where they may be purchased:



You can do a google on wiring harnesses to find more. I love mine with the silverstars. Eric has referred to my headlights as just plain obscene. A compliment of the highest order I'm thinkin!!

My front end lighting without the bambi lights in the grill


Warning - big file!!



Here are three pics of the headlights form TCCA. Stock, Silverstar, and Silverstars and a headlight harness. FWIW

Paul Nimz


    STOCK              Silver Stars         Silver Stars with Harness

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