Using a relay is the best way to go when installing things like lights, etc. Here's a picture of the insides of a typical automotive relay showing the functionality along with the pin numbers.

relay.jpg

With a relay like this, you have 2 sections, the low amperage part that operates the magnet coil on the electromagnet and this pulls down the high amperage switch (contacts). To wire this, you would connect your battery (or an adequate +12V point in your fuse panel or PDC) to a switch, then from the switch, you would go to pin 85 or 86, then you would take the other pin (86 or 85) and wire that to a good ground point - now when you turn the switch on, the relay will "click", connecting pins 30 and 87 (this is your hi-amp switch), so, you would wire pin 30 to your battery (or again, an adequate +12V source) and pin 87, in your case, would go to the lights - the other wire for the lights will go to a really good ground (often the case of the light is considered to be your ground point & if this is how your lights are, you may not have a good ground, but if you have a ground wire around somewhere, add another to it and string that to a good body or chassis ground that you can count on. Now with things wired this way, when you turn on the switch, the lights should come on. Each of the two wires that supply +12V to the relay (hi & lo amp source wires, pin 30 and 85 or 86) should be fused. The lo amp source only needs a couple of amps since it doesn't really take much to activate the electromagnet, but the hi amp side will be a minimum of 10 amps for two 55 watt lamps, but I wouldn't go over 15 amps & don't use less than 14 gauge wire. The basic power equation of Power = Amps * Volts can give you the fuse values if you choose to add anything else.

For any electrical work, I recommend the use of a simple multi-meter, but as a minimum, you shouldn't dive into an electrical project without a simple circuit tester. If you have a couple of "add-a-circuits", you should test them to make sure each one works before you wire them up. The other thing you need to test is your relay - get it to the "click" stage and then check with the circuit tester to make sure the hi-amp switch has closed (pins 30 and 87) & if these parts work, your lights should work as long as you have GOOD grounds.

I wouldn't use less than a 20 amp relay in these circuits, I'd also use a good switch and no less than 14 gauge wire. Pick voltage source points that can handle the amperage you need and life should be good. If you don't know how to hook something up, ask. If you don't ask, you'll end up with a lot of frustration of a burning truck.

 

excellent explanation....show off....lol

 

Thanks jkeaton, it's my pleasure

There are a few relatively simple things that a lot of auto owners involve themselves with that aren't well understood, like relays (wiring in general) and U-joints.