This is a universal harness that is made to power a variety of bulb types and lighting configurations. I obtained the one designed for my sedan with one 9003/H4 bulb per headlight. Harnesses are also available for 9004, 9005, 9006 and 9007 bulbs. The harness appears to utilize 14 AWG (condiderably larger in diameter than OEM) with a fusible link, and contains 4 crimped-on ring terminals; 2 large ones to be connected to the + battery terminal and 2 smaller ones to be connected to the neg battery terminal. The harness also contains a wired-in dual relay socket and a plug with 3 contacts matching a 9003/H4 bulb as well as 2 headlight bulb sockets that will replace the factory sockets. Two heavy duty relays are also included. No instructions were provided. The harness is available from http://www.suvlights.com and the current cost is US $50 plus shipping. The installation was simple but you can download general instructions from the FAQ section of the website. There, you will also find illustrations of the various available harnesses.
The first thing I did was to apply heatsinks to the 4 crimped-on ring terminals and solder them. This makes for a stronger connection than crimping alone and coating the wire strands with solder reduces the possibility of corrosion. After connecting the 2 large ring terminals to the + batt. terminal (which I was able to do by feeding them one at a time through the terminal cover), the relay socket has to be mounted near the left headlight. Conveniently, I found an unused threaded hole in the left inner fenderwell that will take an M6 x 1.0 bolt. The bolt I used was about 25 mm long as I had to space out the relay socket with a couple of nuts and flat washers to get the necessary clearance. I also had to slightly ream out the mounting hole in the relay socket to obtain clearance for the bolt. This makes for a solid, secure mounting.
The next step is to unplug the factory socket from the left headlight bulb and then attach the mating harness plug to that. This step connects the entire factory headlight lighting system to the harness. Then, the harness bulb socket closest to the left headlight is attached to the left headlight bulb. I then ran the harness branch to the right headlight across the valve cover (zip tied to the OEM cable already running there), unplugged the factory headlight bulb socket and attached the second harness bulb socket to the right headlight. The factory socket just hangs there now and is not used. I connected each ground wire terminal from the new harness bulb sockets to the bolts that hold the radiator upper mounting brackets as they were conveniently close.
Before plugging in the relays, the instructions call for applying contact grease to the relay terminals to prevent corrosion. At PEP Boys, I found Permatex Dielectric Tune-Up Grease which, according to Permatex, "Protects electrical connections, ignition parts, and wiring from moisture, salt, dirt and corrosion." I used it on the relay terminals and on the harness plug terminals, applying it with a toothpick, before plugging in. This completes the installation.
With the harness in place, the factory wiring system serves only to energize the relay coils which draw very little current. The heavy headlight bulb current is drawn directly from the battery through the large gauge harness wire and the heavy duty relay contacts. This insures that the bulbs get full voltage and current at all times to maintain their maximum brightness and light output. Another advantage of the modification is that it is easy to return to stock since no permanent modification to the factory system is required. This is strictly a plug 'n play system.
Further Improvements
The original large battery terminals provided with the harness did not provide an optimal connection. Their outside diameter was too large to fit in the channel on the outside of the battery clamp behind the nut forcing me to place the terminals between the clamp halfs - not a good idea because it can result in not getting the clamp tight enough for good contact on the terminal. Furthermore, the mounting holes in the terminals were much larger than the battery terminal bolt size meaning there was not much metal-to-metal contact between clamp and terminals. The battery clamp bolt appears to be an M6 x 1.0 meaning that its diameter is less than 1/4" whereas the diameter of the terminal holes was much greater than that. This is a universal harness after all.
To resolve the problem, I snipped off the original terminals and replaced them with Lightning Audio Bolt BSRT 14/16 AWG gold-plated ring terminals. Two of the 4 terminals included in the package have 5/16" holes and the outer diameter of the rings enables them to fit perfectly in the channel of the battery clamp right behind the nut. This enables the clamp to be properly tightened on the terminal and provides much more metal-to-metal contact than the original terminals, even though the new ones are smaller overall. Because the new terminals are closed end, I drilled them out using a pin vise so that I could both crimp and solder on the new terminals. Some of you might think that overkill - and you might be right. BTW, this job is made easier due to the fact that the fusible link can be unplugged from the rest of the harness.
Happy Motoring!
Photos:
1. Illustrating how the wiring harness (the two smaller black conductors) connects to the battery + terminal.
2. Showing the location of the two relays and the dual relay socket bolted to the left inner fenderwell by means of the unused threaded hole found there. The coolant overflow tank is on the left. The mounting bolt is between the socket and the fenderwell so cannot be seen in this view.
3. The white OEM connector has been unplugged from the driver's side headlight bulb and plugged into the harness' yellow connector (red-white-black wires), on the right of the photo, where it now serves only to provide relay coil current.
The harness' yellow connector (blue-yellow-black wires), on the left side of the photo, replaces the OEM white connector and carries current directly from the battery + terminal, via the relay's power terminals, to energize the headlight bulb. Note the conductor size difference between OEM and harness.
4. The OEM white headlight connector on the passenger side has been disconnected (it just hangs there now) and replaced with the harness' yellow connector (blue-yellow-black wires), providing current directly from the battery + terminal through the relay power terminal. Again, note the discrepancy in conductor size.
5. Black ground wire from driver's side headlight plug connected to the chassis by one of the two radiator upper mounting bracket bolts. Same arrangement for the passenger side headlight plug ground wire.
The first thing I did was to apply heatsinks to the 4 crimped-on ring terminals and solder them. This makes for a stronger connection than crimping alone and coating the wire strands with solder reduces the possibility of corrosion. After connecting the 2 large ring terminals to the + batt. terminal (which I was able to do by feeding them one at a time through the terminal cover), the relay socket has to be mounted near the left headlight. Conveniently, I found an unused threaded hole in the left inner fenderwell that will take an M6 x 1.0 bolt. The bolt I used was about 25 mm long as I had to space out the relay socket with a couple of nuts and flat washers to get the necessary clearance. I also had to slightly ream out the mounting hole in the relay socket to obtain clearance for the bolt. This makes for a solid, secure mounting.
The next step is to unplug the factory socket from the left headlight bulb and then attach the mating harness plug to that. This step connects the entire factory headlight lighting system to the harness. Then, the harness bulb socket closest to the left headlight is attached to the left headlight bulb. I then ran the harness branch to the right headlight across the valve cover (zip tied to the OEM cable already running there), unplugged the factory headlight bulb socket and attached the second harness bulb socket to the right headlight. The factory socket just hangs there now and is not used. I connected each ground wire terminal from the new harness bulb sockets to the bolts that hold the radiator upper mounting brackets as they were conveniently close.
Before plugging in the relays, the instructions call for applying contact grease to the relay terminals to prevent corrosion. At PEP Boys, I found Permatex Dielectric Tune-Up Grease which, according to Permatex, "Protects electrical connections, ignition parts, and wiring from moisture, salt, dirt and corrosion." I used it on the relay terminals and on the harness plug terminals, applying it with a toothpick, before plugging in. This completes the installation.
With the harness in place, the factory wiring system serves only to energize the relay coils which draw very little current. The heavy headlight bulb current is drawn directly from the battery through the large gauge harness wire and the heavy duty relay contacts. This insures that the bulbs get full voltage and current at all times to maintain their maximum brightness and light output. Another advantage of the modification is that it is easy to return to stock since no permanent modification to the factory system is required. This is strictly a plug 'n play system.
Further Improvements
The original large battery terminals provided with the harness did not provide an optimal connection. Their outside diameter was too large to fit in the channel on the outside of the battery clamp behind the nut forcing me to place the terminals between the clamp halfs - not a good idea because it can result in not getting the clamp tight enough for good contact on the terminal. Furthermore, the mounting holes in the terminals were much larger than the battery terminal bolt size meaning there was not much metal-to-metal contact between clamp and terminals. The battery clamp bolt appears to be an M6 x 1.0 meaning that its diameter is less than 1/4" whereas the diameter of the terminal holes was much greater than that. This is a universal harness after all.
To resolve the problem, I snipped off the original terminals and replaced them with Lightning Audio Bolt BSRT 14/16 AWG gold-plated ring terminals. Two of the 4 terminals included in the package have 5/16" holes and the outer diameter of the rings enables them to fit perfectly in the channel of the battery clamp right behind the nut. This enables the clamp to be properly tightened on the terminal and provides much more metal-to-metal contact than the original terminals, even though the new ones are smaller overall. Because the new terminals are closed end, I drilled them out using a pin vise so that I could both crimp and solder on the new terminals. Some of you might think that overkill - and you might be right. BTW, this job is made easier due to the fact that the fusible link can be unplugged from the rest of the harness.
Happy Motoring!
Photos:
1. Illustrating how the wiring harness (the two smaller black conductors) connects to the battery + terminal.
2. Showing the location of the two relays and the dual relay socket bolted to the left inner fenderwell by means of the unused threaded hole found there. The coolant overflow tank is on the left. The mounting bolt is between the socket and the fenderwell so cannot be seen in this view.
3. The white OEM connector has been unplugged from the driver's side headlight bulb and plugged into the harness' yellow connector (red-white-black wires), on the right of the photo, where it now serves only to provide relay coil current.
The harness' yellow connector (blue-yellow-black wires), on the left side of the photo, replaces the OEM white connector and carries current directly from the battery + terminal, via the relay's power terminals, to energize the headlight bulb. Note the conductor size difference between OEM and harness.
4. The OEM white headlight connector on the passenger side has been disconnected (it just hangs there now) and replaced with the harness' yellow connector (blue-yellow-black wires), providing current directly from the battery + terminal through the relay power terminal. Again, note the discrepancy in conductor size.
5. Black ground wire from driver's side headlight plug connected to the chassis by one of the two radiator upper mounting bracket bolts. Same arrangement for the passenger side headlight plug ground wire.
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