2001 pathfinder 451m relay

Those yellow and light green unlock/lock factory wires, set your DMM to DC amps, place your red wire to each in turn with the black wire to ground., do this with all doors closed bar the driver's, hook over the latch in the driver's door, remove or push closed the driver's door contact, rmove the key from the ignition, and in turn place the black probe to ground. If you've done this correctly the vehicle should lock and unlock. Check the draw on the meter. I'm suggesting it will show no more than 120miliamps current draw. This is known as a low neg. Test that "3 prong" junction. On locking 1 terminal will go to ground for about 0.8secs. Ditto with the other on unlocking.  Ignore the middle terminal. That should be sufficient to control your locks although if I was unsure, insert a 1N4004 diode  on each with its band away from the connections. Solder your joints and remember as Chris so rightly says TEST TEST TEST. 

Well I have everything working but the parking lights.  I know the wire is correct because when I turn the parking lights on I get 12V on the wire, and 0 when off.  The polarity of the system should be negative...right?  The dome light works as it should, they why wouldn't the parking lights?  I double checked the setting of the parking lights on the Omega and all should be set correctly.  Any ideas?

Please don't go in for removing unexploded bombs. You said you tested it and it was 12v+ when on, therefore your light feed should be POS.

The locking system is either 3 Wire Negative, or 3 Wire Positive.  I have it set up as a 3 Wire Negative.  With that set up the dome light works.  Both the parking lights and the dome lights work off of the same setup.  The question is...would the dome light still work if I was wrong and the system should be set up as a 3 Wire Positive system?

The SECU should be a silver metal box, just to the left of the steering wheel......behind those three switches on the dashboard that have the dash dimmer.It has three plugs, all of which face down and the wires are are very tight to connect to.It should making clicking sounds internally when you operate the car's power door locks.