QUOTE(double-a @ Apr 20 2004, 06:57 AM)
i'm installing the pilots sometime in the next week or two. can you explain the process for adding a relay... is this like the round black ones? i'm a bit un-initiated electronically, though i did learn a lot by frying my ignition switch and headlight relay recently!
I think you can use the round relays, but it is probably easier to go to an electronics-supply store and get relays and relay sockets from them. They'll likely be cheaper and easier to mount.
A relay is an electrically-operated switch. In a wiring diagram, you will often see it shown as a switch and a coil. When current flows through the coil, the switch gets pulled into one position (for our purposes, that's simply "on"). When current stops flowing, a spring pulls the switch to the other position (for us, "off").
To use a relay to "protect" the ignition switch and headlight switch, you need to do a few things.
First, run a nice beefy wire from the battery to your relay. Put a fuse in that line, preferably within 18" wire run of the battery. Hook it to one of the "switch" connections on the relay. Next, run another beefy wire from the other "switch" connection to the headlights. Hook up the wire that used to go to the headlights, and hook that to one of the "coil" terminals on the relay. Hook the other one of those to ground.
Now, when you turn on the headlight switch, the switch only sends the modest amount of current required to flip the switch inside the relay. That, in turn, handles the larger current that goes to the light.
Now, this gets more complicated in that you have two separate circuits providing power to the headlights, one for high beam and one for low. You can run two relays, one for each, or you can just put the relay on the high-beam circuit. Many people feel that the low beams don't draw enough current to overload the ignition and/or headlight switches, and the simplicity of only having the one relay is worth it. Not sure how I'd do this if I were installing it... Depends in part on how powerful the "target" low beams are.
Speaking of which, you need to size the wires, fuse(s), and relay(s) so that they can handle the maximum draw of the lights. Which depends on the power rating of the lights, and (in the case of the wire size) also the length of wire you will be running.
--DD