I believe the high beam filaments act as the ground at pin 85 on the fog light relay.
Once the high beams are turned on and the lows are off the ground becomes a positive at that pin which gives the relay a positive at pin 85 and no longer a positive at pin 86 deactivating the relay.
Note pin 85 is the connector with 3 white wires, 2 that go directly to the high beams and one from the high/low beam switch. Also note that the right high beam wire in the schematic has a labeling error or errata with its reversal of the description of wire color from “ws “ to “sw “.
The positive at pin 86 comes from the fog light switch directly from the low beam circuit.
So- low beams power the fog light switch which activates the fog light relay.
With low beams off- no fog lights.
With high beams on- no fog lights
Only with low beams on and fog light switch on do you get fog lights.
And if you wire low beams to stay on with high beams you still get no fog lights.
The “toggle” is fog lights go off when low beams go off or high beams go on.
Once the high beams are turned on and the lows are off the ground becomes a positive at that pin which gives the relay a positive at pin 85 and no longer a positive at pin 86 deactivating the relay.
Note pin 85 is the connector with 3 white wires, 2 that go directly to the high beams and one from the high/low beam switch. Also note that the right high beam wire in the schematic has a labeling error or errata with its reversal of the description of wire color from “ws “ to “sw “.
The positive at pin 86 comes from the fog light switch directly from the low beam circuit.
So- low beams power the fog light switch which activates the fog light relay.
With low beams off- no fog lights.
With high beams on- no fog lights
Only with low beams on and fog light switch on do you get fog lights.
And if you wire low beams to stay on with high beams you still get no fog lights.
The “toggle” is fog lights go off when low beams go off or high beams go on.
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