techboj
Well-Known Member
- Joined
- July 19, 2005
- Messages
- 210
- Reaction score
- 0
- City, State
- Surrey, BC Canada
- Year, Model & Trim Level
- 99 Sport + 06 EB
How to: Homemade headlight Wiring Harness upgrade
I apologize since I know this is not the first time this procedure has been discussed. However, I wanted to do a step-by-step instruction for those who want to do these themselves (instead of using the wiring harness posted elsewhere on this site)
You are probably wondering why you would want to do this as opposed to just doing a plug and play installation by purchasing a ready-made harness? For me, I've had bad luck with those 4-prong pilot or asian branded relays. Second, I am unsure whether the wiring harness would be long enough. I also do not like the yellow tubing they use as wire protector (and while I know that this can easily be changed, replacing it would add to the initial cost. Further, the quality of the wire is suspect (not all wire are created equal and some offshore brands that claim at least 14 gauge may actually be smaller and not conform to AWG standards). Finally, I've got all the parts needed anyway, so it seems a lot more rewarding to do it yourself.
Parts needed:
automotive wire - (14 gauge or better, 12 gauge for power)
automotive relay - (bosch type 4 or 5 prong) at least 2
relay sockets - for easier wiring of relay (can also use female spade terminal connector)
switch (optional) - to be discussed later) - type depends on preference
split loom tubing - 1/4 or 3/8" (I prefer black for an oem look)
electrical tape - color of your choice (again I prefer black for oem look)
inline fuse holder - pref two (I used ATM holders so I do not have to carry different additional fuse types
9007 female lamp sockets x2 - (I had a few of these from a donor mustang) - oem should be fine but you can upgrade this to ceramics if you want
9007 male lamp socket x 1 - (you can use an old broken 9007 bulb)
heat shrink tubing
hot glue gun (optional but recommended)
basic tools - soldering iron, needle nose pliers, wire strippers
The first thing I did was to get an old 9007 bulb. I have a few of these lying around with only the high beams working. I usually keep them since sometimes the o-ring from newer bulbs is so tight (or too hard) to go into the headlight housing so I swap them around.
Carefully separate the bulb from the 9007 base. Most bulbs are held by small tabs electro-welded to a ring around the base. You do not need a lot of force to remove these tack-welds. A slight twist with a needle nose plier is enough to detach them. Do remember that the gas inside is pressurized so always wear eye protection and gloves when doing this.
Once the tabs are removed, you will see three wires leading to the bulb filaments. Take cutter pliers and snip off the bulb retaining as much as you can of the three internal wires. Remove the bulb retaining ring as well to make more room
.
Once you've got the base detached, solder automotive wire (about a foot and a half each) to each of the wires on the socket. You can bend or make a small loop on the end of the wires. These wires can use small gauge automotive wires since these would only serve as "triggers" and not carry a lot of current. Make sure your connections are good and then insulate the wires. I used heat shrink tubing and then filled the gap with hot glue to make sure none of the wires move.
Prepare wires. Unfortunately I didn't really measure the length and just eye-balled the length I needed. I cut my wire measuring from the passenger side headlight to about a foot after the battery. (This will be the load wire and will be the longest wire on the harness).
Wire the Relays as illustrated in the diagram. Poles 85 and 86 can be interchanged. It is always easier to use pre-wired relay sockets but you can use plug-in spade connectors if the sockets are not available. For the harness, each terminal 30 goes to individual inline fuse holders. Terminal 85 of the relay goes to the negative central terminal of the modded 9007 headlight male socket. Terminal 86 of one relay will pick-up signal from the low side while the other relay will get its signal from the high beam trigger wire. I used Jaguar LJA6703AA relays. You can use any type of relay but I had a few dozen of these lying around (plus their matching sockets). They seem to be of better quality and are rated up to 40A each. The only problem with these relays is that they do not use the same numbering as standard bosch relays. Bosch are numbered as 85,86,87 and 30. The Jaguar relays are numbered 1,2,3 and 5. The good thing is that they would snap into regular bosch sockets and the pins would correspond to the correct wiring where pin 1 = 86, 2 = 85, 3 = 30 and 5 = 87.
Connect the 9007 OEM sockets (obtained from a mustang / taurus) to the harness. You can use new aftermarket sockets or even ceramic sockets (specially if you intend to use higher wattage bulbs)
When connecting wire together, properly solder and use heat shrink for protection. All the wires used are gauge 14 or better.
When all the wires are connected and insulated, everything was covered with split loom tubing and then finally electrical tape for even better water resistance.
The total length of the harness I made is about 9 feet end-to-end (This is from the end of the male 9007 socket to the end of the inline fuses.
Picture below show the location of the relay and inline fuses. I covered the relays with tape for additional water protection. The third relay is the relay for the aftermarket driving lights/foglights.
This is the "before" picture without the upgraded harness. Bulbs are silverstars with OEM headlight housing. The three driving lights are kc style knock-offs made by blazer. They originally had 100 watt bulbs but I substituted them with more street-friendly 55 watt hella bulbs.
After installation, there was a marked improvement in brightness (although I have no means of measuring it quantitatively) but it's probably safe to say 10-15% (possibly more) with the same silverstar bulbs. (Sorry for the poor picture = raining really hard). Picture below is with the low beams
If you notice on my parts list, I included an optional switch. For those with DRL, you can interrupt any of the wires leading to the relay but preferably 85 or 86) so that when you have your aftermarket driving lights / foglights on, you can turn off your headlights. In my case, my non-oem foglights are triggered by the low beam circuit. Hence, I can interrupt this circuit and leave the foglights with the low beam headlights off.
I apologize since I know this is not the first time this procedure has been discussed. However, I wanted to do a step-by-step instruction for those who want to do these themselves (instead of using the wiring harness posted elsewhere on this site)
You are probably wondering why you would want to do this as opposed to just doing a plug and play installation by purchasing a ready-made harness? For me, I've had bad luck with those 4-prong pilot or asian branded relays. Second, I am unsure whether the wiring harness would be long enough. I also do not like the yellow tubing they use as wire protector (and while I know that this can easily be changed, replacing it would add to the initial cost. Further, the quality of the wire is suspect (not all wire are created equal and some offshore brands that claim at least 14 gauge may actually be smaller and not conform to AWG standards). Finally, I've got all the parts needed anyway, so it seems a lot more rewarding to do it yourself.
Parts needed:
automotive wire - (14 gauge or better, 12 gauge for power)
automotive relay - (bosch type 4 or 5 prong) at least 2
relay sockets - for easier wiring of relay (can also use female spade terminal connector)
switch (optional) - to be discussed later) - type depends on preference
split loom tubing - 1/4 or 3/8" (I prefer black for an oem look)
electrical tape - color of your choice (again I prefer black for oem look)
inline fuse holder - pref two (I used ATM holders so I do not have to carry different additional fuse types
9007 female lamp sockets x2 - (I had a few of these from a donor mustang) - oem should be fine but you can upgrade this to ceramics if you want
9007 male lamp socket x 1 - (you can use an old broken 9007 bulb)
heat shrink tubing
hot glue gun (optional but recommended)
basic tools - soldering iron, needle nose pliers, wire strippers
The first thing I did was to get an old 9007 bulb. I have a few of these lying around with only the high beams working. I usually keep them since sometimes the o-ring from newer bulbs is so tight (or too hard) to go into the headlight housing so I swap them around.
Carefully separate the bulb from the 9007 base. Most bulbs are held by small tabs electro-welded to a ring around the base. You do not need a lot of force to remove these tack-welds. A slight twist with a needle nose plier is enough to detach them. Do remember that the gas inside is pressurized so always wear eye protection and gloves when doing this.
Once the tabs are removed, you will see three wires leading to the bulb filaments. Take cutter pliers and snip off the bulb retaining as much as you can of the three internal wires. Remove the bulb retaining ring as well to make more room
.Once you've got the base detached, solder automotive wire (about a foot and a half each) to each of the wires on the socket. You can bend or make a small loop on the end of the wires. These wires can use small gauge automotive wires since these would only serve as "triggers" and not carry a lot of current. Make sure your connections are good and then insulate the wires. I used heat shrink tubing and then filled the gap with hot glue to make sure none of the wires move.
Prepare wires. Unfortunately I didn't really measure the length and just eye-balled the length I needed. I cut my wire measuring from the passenger side headlight to about a foot after the battery. (This will be the load wire and will be the longest wire on the harness).
Wire the Relays as illustrated in the diagram. Poles 85 and 86 can be interchanged. It is always easier to use pre-wired relay sockets but you can use plug-in spade connectors if the sockets are not available. For the harness, each terminal 30 goes to individual inline fuse holders. Terminal 85 of the relay goes to the negative central terminal of the modded 9007 headlight male socket. Terminal 86 of one relay will pick-up signal from the low side while the other relay will get its signal from the high beam trigger wire. I used Jaguar LJA6703AA relays. You can use any type of relay but I had a few dozen of these lying around (plus their matching sockets). They seem to be of better quality and are rated up to 40A each. The only problem with these relays is that they do not use the same numbering as standard bosch relays. Bosch are numbered as 85,86,87 and 30. The Jaguar relays are numbered 1,2,3 and 5. The good thing is that they would snap into regular bosch sockets and the pins would correspond to the correct wiring where pin 1 = 86, 2 = 85, 3 = 30 and 5 = 87.
Connect the 9007 OEM sockets (obtained from a mustang / taurus) to the harness. You can use new aftermarket sockets or even ceramic sockets (specially if you intend to use higher wattage bulbs)
When connecting wire together, properly solder and use heat shrink for protection. All the wires used are gauge 14 or better.
When all the wires are connected and insulated, everything was covered with split loom tubing and then finally electrical tape for even better water resistance.
The total length of the harness I made is about 9 feet end-to-end (This is from the end of the male 9007 socket to the end of the inline fuses.
Picture below show the location of the relay and inline fuses. I covered the relays with tape for additional water protection. The third relay is the relay for the aftermarket driving lights/foglights.
This is the "before" picture without the upgraded harness. Bulbs are silverstars with OEM headlight housing. The three driving lights are kc style knock-offs made by blazer. They originally had 100 watt bulbs but I substituted them with more street-friendly 55 watt hella bulbs.
After installation, there was a marked improvement in brightness (although I have no means of measuring it quantitatively) but it's probably safe to say 10-15% (possibly more) with the same silverstar bulbs. (Sorry for the poor picture = raining really hard). Picture below is with the low beams
If you notice on my parts list, I included an optional switch. For those with DRL, you can interrupt any of the wires leading to the relay but preferably 85 or 86) so that when you have your aftermarket driving lights / foglights on, you can turn off your headlights. In my case, my non-oem foglights are triggered by the low beam circuit. Hence, I can interrupt this circuit and leave the foglights with the low beam headlights off.
