Visitor # 26262 since 28.AUG.2001
The stock 6054 sealed beam headlights in my '82 Caddy were pretty dismal. I remember more than one time getting out to see if they had burned out as I could not see any light on the road in front of me (unfortunately they were not burned out :). So, I decided to swap them out for a halogen lamp. For a while I used a set of Hella Vision Plus, H4 halogen replacement lamps. They worked great, but later I grabbed them and installed them in my 4x4 Toyota (since I tend to drive that in bad weather and very dark backcountry roads).
For the Caddy, I decided to get something different. I picked up a set of sealed beam halogen Philips Color Clear lights. I chose them mainly for the black-out color when they are off, they sort of blend into the black grill on my Caddy (see photo below). Also, the black grill inside the housing really cuts down on glare and the lights work just fine for my needs. The only drawback of the internal grill is that it cuts down on the light output a bit, so the extra current I would get with a headlight relay kit is just the ticket. These lights are no longer made, but I have my working pair and a spare lamp, so I'll make do with them for now. With a sealed beam lamp, upgrading the bulb is not an option, so increasing the power to the light bulb is the only way to go.
After installing a headlight relay kit in my 4Runner, and seeing the skimpy stock wiring and convoluted path that the headlight current takes, I decided it was time to upgrade the system wiring. To re-iterate, this was done on the stock, factory headlight wiring harness, I had made no modifications to it, aside from replacing the old sealed beams with the some Philips Color Clear sealed beam halogen headlights. Besides improving the light output, the relays will take the load of switching the high current of the headlights off the old factory headlight switch. This part is no longer available from VW so if it wears out, the junkyard is the only option to replace it. And if I ever do decide to upgrade to higher output lamps, I'm all set!
Now, I'm an Electrical Engineer, I can easily design and build a relay setup for the headlights, but I really hate working on automotive wiring, and don't do it very well, I tend to rush and the end result, while functional, is not pretty. For something as important as headlights, I decided to buy rather than build (plus I had been "thinking" about building a relay harness for many years, but had never even started). So armed with the knowledge that VW headlights operated on a switched power system (i.e. the common connection of the bulbs is grounded and the power is supplied to one or the other filament to light the bulb), and that I use H4 style headlights in my '82 Caddy, I found a nice looking and well designed wiring harness kit that seemed to fit my needs, it supports 2 - H4 style headlights (one on each side) and works off of the switched power system that VW uses:
Pictured above is a 9004-style, switched power harness, but its very similar to the H4 harness I used. The blue connector looks like the back of a headlight bulb and you simply connect one of the existing headlight connectors to it. The harness is designed to accomodate headlight separations of nearly 6 ft. so should fit most common vehicles.
So on to the installation:
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| A: Headlight Wiring Harness Connection Note: The H4 style connector (3-wire) |
This connection (A) supplies the control power to the two relays in the new harness, you just plug one of the stock (dirty yellow colored) headlight connectors (female H4) into the (bright yellow) mating connector (male H4) on the new harness. It can only go in one way and there is only one male H4 connector, so its hard to get this step wrong! Since this connector is close to the relays, which in turn have to be close to the power source. its best to use the headlight connector nearest where you intend to tap into power. Since I tapped into power at the engine fuse block, I used the passenger side light, your installation may be different. The 9004 harness installing is similar, just match up the male and female 9004 connectors in the same manner as the H4 connectors.
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| B: New Relays and Fuse Block Connection |
C: Stock H4 Connector (unused) New H4 Connector Installed |
Then you connect the power leads, via a fuse (I used a single 30A fuse in my auxiliary fuse block, but two separate 20A fuses would also work well) to power (picture B - if no fuse block handy, you can run a fused wire off the battery or off the engine fuse box as needed), then attach the two ground connections to the frame or body near by the headlights. I found a couple of body bolts that were a good ground points. Finally, plug the two new connectors into the headlights (C) and you are done.
So how well does the system work? In my opinion, it works great. The relays are socketed for easy replacement if needed, and I like the fact that I can revert to stock just by swapping back to the old headlight connectors, handy if a relay dies on a long road trip, or I want to move the harness to a new vehicle. All the wires are run in protective looms, and everything is straight point-to-point connections, no splices or other mid-wire breaks.
For a quick test of how effective the harness is, I used a volt meter across the headlight bulb to measure the actual voltage drop at the filaments (or as close as I can get to them:). With the stock harness, I measured 10.6v and with the new harness, I got 12.6v. May not seem like a huge difference, but light output is proportional to the square of the voltage, so (12.6/10.6)^2 is about 41% more light, for the same bulb no less. Pretty good for a $39.00 harness and a few minutes of installation time. In fact, the light output of the sealed beam halogen head lamps I had in there was increased to the point that I decided it was not worth it to change the lamps out, at least until those sealed beams burned out. As they say, "if it ain't broke, don't fix it!"
One thing to consider with halogen bulbs is that they last longer when run as hot as possible. The halogen gas inside the lamp forces the metal ions back towards the filament to redeposit them and increase the light output. When run too cool, this mechanism doesn't work as well so the bulbs burn out faster and give less light. This is sort of the opposite for normal light bulbs, they generally last longer at lower voltages. On the other hand, all the wiring harness is doing is supplying more of the system voltage that the bulb was designed for to the bulb. You will not get any more voltage than the vehicle's charging system is capable of delivering even if you used huge cables or even super conducting wires. So in no way will the harness lead to a light burning out from too much voltage.
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| A: H4-style Connectors | B: 9004-style Connectors |
Bottom line:
This headlight wiring harness is in stock and ready to ship! Feel free to contact Missing LinkZ if interested in more info.
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| Dual H4 Style Harness, Switched Power, US Delivery | Dual 9004 Style Harness, Switched Power, US Delivery |
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| Dual H4 Style Harness, Switched Power, Int'l Delivery - A telephone number is required for customs paperwork - add it in the Note To Seller field of the order form |
Dual 9004 Style Harness, Switched Power, Int'l Delivery - A telephone number is required for customs paperwork - add it in the Note To Seller field of the order form |
Notes:
If you want to make your own relay wiring harness or convert from one type of headlights to another? No problem. Usually most of the items needed are available like wire, relays, replacement headlight connectors (female), but if you have trouble locating any of those items, we stock a small supply of Bosch-style headlight relay sockets, 30 and 40 amp headlight relays, and female H4 and 9004/9007 headlight sockets.
The hard to find item is the male connector that mates the relay harness into the existing wiring. Now they are avialble in both an H4-male and 9004/7-male connector shell with pins that you can use to make your own harness or use to convert one type of headlight to another. For example, if you have a 9004/7-equipped vehicle and want to upgrade to H4 headlights, order the H4 harness and the 9004/7-male connector and then swap the H4-male connector on the relay harness for the 9004/7-male connector and you are set and have made no changes to the factory wiring. The relays will be controlled via the 9004/7 factory wiring and will send their output to the new H4 connectors on the harness to the new headlights. The 9004 and 9007 headlights share the same physical connector shell, but the high/low/common pins are swapped, so depending on how you wire up the connector shell will determine if it is a 9004 or 9007 type of connector.
The male connectors cost US$12.00/ea. or 2 for US$20.00 plus shipping.
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| H4-male | 9004/7-male |
Also available are female H4 and 9004 connectors as well as relays (30 and 40 amp) and relay sockets.
In some cases, you may find you need to change the type of headlights in your vehicle. For example, you may have a 9004 headlight currently, but want to upgrade to a more widely available H4 setup. To do so, you need to change out the headlight connectors. Instead of swapping out both headlight connectors, another option is to use a relay wiring harness kit, that is also built to convert the type of connector as well. For example, if the harness were set up with a male 9004 connector to mate with the original 9004 connector in the vehicle, and if it had female H4 connectors for the new headlights, you could install the harness with no changes to the factory wiring, a true plug-n-play installation. If you want an H4 or 9004 harness pre-configured with an opposite (9004 or H4) male connector, that can also be done for a cost of $25.00 on top of the cost of the relay harness (see above). More information available via e-mail.
[Last updated: 07.January.2008]