For one or both of two basic reasons. The high beam output from the switch will go to pin 85 of the relay instead of to the headlight's high beam lug. If you have no idea why you might even want to do that, let alone how to do it, read on. It is not my fault if you fry yourself, anyone else, or your car. These relays cost no extra to have that pin so don't worry about that part.
It is also in my photo's on my profile page. Making a or a for some work or an item for sale? Make sure it does not interfere with anything like closing the hood or getting to anything else you may need to service on the engine in the future. So read on and learn how to do this. You can use this as an additional output for fog lights or other running lights that will shut off when the high beams are switched on, but you must use an additional relay for those. That resistance sucks up electrical energy that could be used to produce light at the headlights, so your lights are dimmer than they could be. I am banking on my first guess! Relay Diagram Bottom View Use a 1N4000 series diode available at Radio Shack and other electronics stores as a drain for static electricity that builds up from deactivating the coil. If this is gibberish to you, don't worry about it - it was just the elitist purists trying to confuse you.
It started out happening for a little while then they would come on, and other times I can drive over ten miles and no change. If possible, mount the relay solidly either rivet or screw it to the headlight bucket or use a wire tie or tie strap to connect it as solidly as possible. If stuff starts smoking or melting, disconnect the battery right away and figure out what you messed up and fix it before reconnecting it again. The wiring diagram was always correct, but the headlight labels may have been a tad confusing to some. If you know what that means, now you know.
Grounding the headlight through the shell or bucket can at the least cause the headlight to flicker, not be at full strength, burn out faster and in extreme cases can cause your steering head bearings to seize rare, but it can happen. I did not tell you that you should do this - only that you could do this. The other 2 can be reversed on some bulbs kind of odd, but true. Here, I will try to make it easier. This is where a relay comes in. Note that in the following diagrams, a fuse is not shown, but a fuse is always needed.
I know about this, but it's confusing to most people and not relevant to the discussion here. There are many others on this site who may be familiar with your truck that may jump in at at any time. That's the difference between being able to see to stop in time and having an accident - so this is a very useful safety and drivability modification. You must also use the appropriate sized power wires and you may very well end up replacing all of the headlight wiring from the relays out to the headlights themselves - don't forget to upgrade to a larger headlight ground if you do this! I went with the 2500. Keeping the fuses close to the power source eliminates long stretches of unprotected circuitry. The coil creates a magnetic field which turns back on itself when power is removed, creating a power surge of little current but very high voltage.
The first is that you have installed high output headlights off-road units, etc. It sounds like some odd-ball electrical problem you have there. If you are attempting to make parts from one vehicle work in another vehicle, get both manuals, strictly for figuring out what wire serves what function and so you know what to connect to where and what to eliminate. This is not required, but it will save some of your components from possible electrical damage. A general rule of thumb on fuse sizes is 10% more than the load limit of the accessory being fused.
These lights were popular in quite a few American vehicles in the late 70's and the 80's and some American trucks like the Western Star, Kenworth and some Peterbilts. Safety tips and application data The standard set of safety disclaimers apply - this is for your information only and none of this should be attempted unless you are sure you know what you're doing. To put this into perspective, a 10% drop in voltage between the battery and the headlight is not uncommon - and that can cause up to a 30% drop in light output! Most vehicles use a ground output to activate a horn, yet most horns are physically grounded to the body or chassis, making a ground switched input useless. The hardest part of all this is typically finding the right wires in the existing wiring harness and finding a place to mount the relays - the actual wiring is pretty easy. This is not an option. Turn Signals: One Switch: Two Switches: Fuses: Remember to always add a fuse to every individual circuit you create or add to the existing harness. If any problems occur, turn off the headlights and unhook the battery immediately - then find and fix the problem.
Run a new 14 gauge wire fused, of course. A 10 or 15 amp fuse should be fine, depending on the power requirements of your headlight. An auto parts store should have that whole pigtail and also have butt splices to connect the wires back together. A basic example of this is a horn in most cars and trucks. It needs to be done exactly as the diagram shows and does work well. This was both annoying and downright unsafe - so I fixed it with this change. When I turned off the ignition and opened the door then shut it, came back to check again and they came on.