According to the diagram I pulled it's a brown wire that goes all the way from the parking light relay to the lights themselves. Black being the ground.
What colors do you have at the socket?
Do you have a meter or a test light?
That third wire is probably the one that daisy chains the light to the other park/signal bulb. Try looking at the harness before it gets connected to the light itself too. Maybe it's brown there but changes at the plug just before the light.
Last edited by CruisinG6; 12-20-2013 at 01:18 PM.