i know that the fog light lamps connect to a harness that converges into a plug, this plug - plugs into a relay that end with 4 wires (1 black thick wire , 1 white thick wire, 1 black thin wire , 1 white thin wire). I assume the thick black and thick go to battery and ground. this is where i get confused so now i have 1 thin white and thin black wire left.

that connects to another harness this harness on one end has the on off switch at the other end of the harness are 3 wires 2 thin white and 1 black thin wire.

why is there an extra thin white wire? does this extra white wire splice into running light?? can anyone confirm thanks


and if it does splice into running lights how do i know which white wire it is?

 

it splices into a key on source

 

thanks.