Welcome, I am Chris (aka-Moose)
At the combination switch. With the fog lights commanded on. Check the red/yellow wire at pin 2 ( there are 2 red/yellow wires, the other is pin 9 which is next to a red and white/black wire). Pin 2 should be a ground, if it is not then supply a ground wire to this wire, the fog lights should come on if the relay is good. If pin 2 is not a ground, check the green/orange wire, if it is a ground then the combination switch is bad. Can you do these tests?
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