This is cut and paste from an earlier post of mine on the same question.
Do a search here and you will find lots of info on wiring OEM binnacle switches. Best to search using 'binnacle'. I have a note below on how you get them to come on with high-beam instead of low-beam. The relay basically taps into the headlight harness and splices into either the low-beam or high-beam wire. If its now connected to low-beam wire - just remove that and re-splice to the high-beam wire. I forgot the wire color for each but the low and high-beam wires are the heavier gauge wires in the headlight harness (there are only two heavier gauge wires there - just switch them or seach some more here and get the right color code). Here is some info I have posted before:
I just got this all wired up - front fogs and 2 rack lights.
The binnacle switches have 5 pins as mentioned and are labeled (numbered):
Pin 1 - connect to power source (highbeam wire if you want switch to only work with highbeams, battery for use all the time, etc...)
Pin 2 - power for light on switch - I just tapped into wire from adjacent switch going to pin2
Pin 3 - empty (unused)
Pin 4 - connect to relay on your lighting set-up
Pin 5 - Grnd
This was mentioned above also so just confirming and adding some more detail. Got my switches and connectors from EE and they were very helpful. Also note there is some mis-information out there on these pin configs so use this info.
In this set-up, you basically need only 3 wires coming into your dash/binnacle area for the switches. One for wire from power source (highbeam wire, battery, etc..). One wire from relay. One wire for ground. I always run separate wires for grounds for all lighting as this is best way to ensure clean ground and no issues down the road. The pin 2 wire can just be spliced from pin 2 on an adjacent switch as this is just powering the switch light illumination.
On my PIAA set-up, there is a PIAA toggle switch that comes with the kit and connects to the relay. Since I used the factory OEM binnacle switches, I had to cut off the PIAA toggle switch (not use it). There are three wires going to the PIAA toggle switch (I assume same for Hellas). One is power, one is ground, and one is relay. These three wires directly relate to the 3 wires referenced above as required to be run to the binnacle area. So, just run the 3 new wires to the binnacle and splice the 3 wires from the light switch. I did this on the DS firewall area as I routed the new binnacle switch wires thru the factory wiring harness/gromit located on the DS florr area on my DII.
AndrewT
