Very interesting! posted by Red Hawk (CO) on January 11, 2013 at 02:24 PM
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Fogs did work w/ parking and low beams; and finally fogs did not work in high beam (because the dimmer relay cuts power to fogs when high beam is activated). As a result of grounding pin 18 behind the fog light switch, I can now get the fogs to work in in off, when no other lights are switched on, like DRLs. I think grounding pin 18 (G/Y) is a quick way of closing the Fog Relay Coil grounding loop; as opossed to the circuit running up into the Dimmer Relay and I think also through the Pass side headlight relay.