If I am thinking correctly, the blue wire will illuminate the switch in question. If there is another switch near by that illuminates when the headlights are on I would try and find that switches source of power during illumination and run the blue wire off that wire. Hopefully that makes sense.This is what i have. Red/green/blue/black
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I emailed aob because their instructions do not match the pigtail supplied. Their response,
“red power in from fuse box
green power out to activate the relay
blue is for dash lights (optional)
black to ground”
Still leaves me wondering where to connect the blue wire.