head light upgrade

I have a 57 chevy. It uses a single high/low beam bulb. I am planning to upgrade to H4 bulbs that will draw more current then the old bulbs. The head light switch supplies power to the dimmer switch, which then puts power to either the low or high beam wires. How do I add relays to make the current draw across the relay terminals & not the head light switch or the dimmer switch?

a relay is a wonderfull thing, you use your existing wiring to switch the relay which only takes millamps to run. to hook up your relays you can either use one or two, i recomend you use two, your lights will be brighter, to wire these relays use this as wiring. hook a wire from your battery to 30/50 terminal, normally red on a relay harness, put a 20amp in line fuse to protect the circuit, hook terminal 87, white, to your lights. this is the circuit that powers the lights,{high amp power}, next you need to ground the relay, 86 terminal ,green, you than hook your dimmer switch wire to 85 terminal, black, it requires minimal amps to run these two wires and it will have a smaller load on your dimmer switch or light switch than stock. i have put in hundreds of these things for clients, the closer you keep these relays to your lights, thus making the battery 30/50 wire and the 87 wires as short as possible, causing less resistance making lights brighter. note 87 is normally open meaning it will close 30/50 to 87 when power is applied to switch, 87a is normally closed and will open when switch power is supplied. some relays have different coloured wires put all terminals are labeled. have fun and good luck

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billybob

Don't forget about the Dimmer switch and Tail lights. I would wire the relays near the headlamps with a larger wire size to handle the extra load.

One relay for High and one for low. Light green and Tan

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Here is the modified diagram condinsed

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !