What size fuse protects the horn circuit?

A 30A fuse in the engine compartment fuse box (page 13-21), which is hot at all times.

What wire colors are used in the horn circuit?

Circuit 460 V/LB feeds the horn relay, circuit 6 V/LG runs from the relay to the horns, and circuit 1 DB is the relay control/ground path through the horn switch.

How does the horn switch make the horns sound?

Per the diagram callout, when the horn switch is closed it allows current flow to sound the horn; the switch side of the circuit drops to 0V when the horn switch is depressed, energizing the relay, which directs voltage to sound the high and low pitch horns.

Which connectors serve the high and low pitch horns?

The high pitch horn uses connector C1006 and the low pitch horn uses connector C1005, both fed by circuit 6 V/LG at 12V when the relay is energized.

What other systems share the horn circuit wiring?

From splice S208 on circuit 1 DB, branches go to the keyless entry system (page 111-1) and anti-theft system (page 112-2); the horn switch is part of the speed control/horn switch assembly (page 31-1).

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Ford Horn Relay Wiring Diagram & Horn Switch Bypass - High/Low Pitch Horns

Horn circuit wiring diagram with relay, fuse box, switch and high/low pitch horns

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Wiring diagram of the horn circuit showing the horn relay, fuse box, keyless entry and high and low pitch horns.

AI caption July 2010 · Photo 9 of 9

This document is a two-panel horn circuit wiring diagram, apparently taken from a Ford EVTM (Electrical & Vacuum Troubleshooting Manual) and modified to show a horn switch bypass. The left panel shows the factory horn circuit: a hot-at-all-times 30A fuse in the engine compartment fuse box (page 13-21) feeds the horn relay via circuit 460 V/LB. The relay, when energized, directs 12V through circuit 6 V/LG to the high pitch horn (connector C1006) and low pitch horn (connector C1005). The relay coil ground path runs through circuit 1 DB via connector C202 and splice S208 (with branches to keyless entry, page 111-1, and anti-theft, page 112-2), then through connector C219 to the speed control/horn switch assembly (page 31-1), including the clock spring, horn switch, and brush; the switch reads 0V when depressed. The right panel shows the same upper circuit, but the factory clock-spring horn switch section is replaced by a photograph of a simple aftermarket push-button switch, illustrating how to bypass the steering-wheel horn switch by grounding the 1 DB circuit directly. Useful for diagnosing horn faults or wiring a substitute horn button.

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Frequently asked questions

What size fuse protects the horn circuit?: A 30A fuse in the engine compartment fuse box (page 13-21), which is hot at all times.
What wire colors are used in the horn circuit?: Circuit 460 V/LB feeds the horn relay, circuit 6 V/LG runs from the relay to the horns, and circuit 1 DB is the relay control/ground path through the horn switch.
How does the horn switch make the horns sound?: Per the diagram callout, when the horn switch is closed it allows current flow to sound the horn; the switch side of the circuit drops to 0V when the horn switch is depressed, energizing the relay, which directs voltage to sound the high and low pitch horns.
Which connectors serve the high and low pitch horns?: The high pitch horn uses connector C1006 and the low pitch horn uses connector C1005, both fed by circuit 6 V/LG at 12V when the relay is energized.
What other systems share the horn circuit wiring?: From splice S208 on circuit 1 DB, branches go to the keyless entry system (page 111-1) and anti-theft system (page 112-2); the horn switch is part of the speed control/horn switch assembly (page 31-1).