When you pull the light switch on, electricity goes from the accessory power line (off the positive post with a fusible link) to the high-low switch. The high-low switch either sends power on one pair of wires to both headlights for low beams or on another pair for high beams. Each light has a ground wire.
1976 FJ55 wiring schematic in PDF format
1976 FJ55 wiring schematic in GIF format
I read this page and kind of used it as my map.
What Chris Alger and I did was to expose the insulation on the high and low beam power wires for the passenger-side headlight, connect 16ga wires from them to two Hella relays. We also sent power straight from the positive post to the two relays, with 20amp blade fuses in-line across 10ga wire. Chris made a little bracket for the firewall on which to mount the relays and we grounded them locally. Then we sent one hot wire out from each relay to the two high beam and two low beam bulbs. This is where the three-way connection comes in. The original headlight connectors are disconnected and not used. I used these nifty Hella connectors with spring-loaded teeth that capture the three wires and offer a female headlight socket to the lights.
I've read that 100w headlights will draw more power than a stock headlight switch is built to handle, and they won't get enough amps from the stock harness if the switch doesn't fail. This setup sends as much power as needed from the battery to the lights. The relay lets the power through, or not, like a lock in a canal. The relay is triggered by the power flowing through the hi/lo switch, which was meant for the passenger-side light but is redirected to the two relays.
Here are some pics:
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Morgan Fletcher
<morgan@off-road.com> Last modified: Fri Jun 15 12:08:07 PDT 2001 |
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