Originally Posted by TOKSICK

I have to play around with it today to see if I can figure out what it's for as well.

The little sheet just showed where you are supposed to find install guide, but since the 370 headlights are not on the Morimoto site, there isn't much to find.

I looked at the F150 and C6 Corvette guides to try and figure out what it could be for. Those both use the fuse box instead of battery for their extra harness. Both list that it is for the daytime running light. Having that smaller plug disconnected is how they show it for the sequential turn signal. Connected is for standard blinking.

The extra harness is probably for the drl. I dont currently have both lights in and only tested the one Morimoto light with the headlights on, then high beam on and checked if blinker worked.