Auxiliary lights relay wiring diagram with battery, fuse, relay…

Aux Lights Circuit

A safe, reliable circuit for adding auxilliary lights. A common 30A Bosch/ISO relay will handle up to 6 55W bulbs using a 30A fuse. A pair of 55W bulbs only requires a 10A fuse. The 3A fuse is only necessary if the new relay is on the other side of the firewall from the splice to the Br wire.

The "ON" setting of the dash switch is actually "AUTO" since it allows the main headlight switch to control the aux lights as if they were part of the original design.

See also:

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https://www.fleet.ford.com/truckbbas/non-html/1997/c37_39_p.pdf

Owner caption September 2008 · Photo 2320 of 5000