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Old 06-26-2012, 07:45 AM   #17
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Location: Marion, IA
What I Drive: 2012 Ford Focus S Ingot Silver

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Originally Posted by JL330 View Post
How does the factory fog light switch work? It may still be possible to do an aftermarket type of wiring and still use a factory switch. I'm still in for a write up on having fogs in this car.
The switch is fully digital. When you turn the headlights on or press a function on the switch it sends a data command to the BCM which in turn carries out whatever function the driver wanted. All the lights themselves are switched on and off via relays inside the BCM. the connector for the light switch has only 3 active connections... 22 gauge power in, 22 gauge ground, and a 22 gauge data wire going to the bcm. the switch uses Pulse coded modulation.
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