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Rock Lights Relay Wiring Diagram - Dome Light Auto/Manual Switch, 20A Fuse

Wiring diagram showing rock lights wired through a DPST switch and relay with color-coded pins and a 20A fuse to 12V.

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This is a hand-drawn wiring diagram (watermarked "Adrianspeeder") for adding rock lights to a vehicle, uploaded to a 1988 Ford Bronco gallery. It shows a double pole single throw switch with three positions: Automatic, Off, and Manual. In the Automatic position, the circuit ties into the dome light wire so the rock lights come on with the interior light; in Manual, the lights are powered directly from the 12V battery through a 20-amp fuse. A standard automotive relay is used with its terminals labeled by number and wire color: 85 (blue) to ground/switch, 86 (green) to the switch, 30 (red) feeding the rock lights, and 87 (yellow) to the fused 12V positive supply. Two rock light lamps are shown wired in parallel, each with its own chassis ground. The diagram teaches a reader which relay pins to use, what wire colors the author assigned, the recommended 20A fuse size, and how to wire a three-position switch for automatic (dome-light-triggered) or manual operation of auxiliary rock lights. No year, make, model, or part numbers are stated in the diagram itself.

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Frequently asked questions

What fuse size does this rock light wiring diagram call for?
A 20-amp (20a) fuse inline between the 12V battery positive and the relay/switch circuit.
Which relay terminals are used and what wire colors go to them?
Terminal 85 (blue) goes toward ground/switch, 86 (green) to the switch, 30 (red) feeds the rock lights, and 87 (yellow) connects to the fused 12V supply.
What type of switch is used for the rock lights?
A double pole single throw switch with three positions: Automatic, Off, and Manual.
How does the Automatic mode work?
In Automatic, the switch connects the circuit to the dome light wire, so the rock lights operate along with the dome light.
How are the rock lights themselves wired?
Two rock lights are wired in parallel off relay terminal 30 (red), with each light grounded separately to chassis ground.

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