dispute over which wire

I tend to think I hold my own when it comes to installing alarm systems. Recently while testing a new system I was hooking it up on a shop truck [2004 chevy exspress cargo van] I opted to try out the built in relay for the parking light flash and tied into a neg wire i found located in the trucks BCM [right now my color of it is out running around in the van] Also I used a the white wire located on the brake switch for the brake wire since this was a combo alarm/starter. Well the system started out fine the parking lights worked like a charm, but then it failed to remote start the van a few times. My partner checked it out and he said I should have used the brown + on the light swich and the purple wire on the brake switch. well after changing the jumper on the system I tied into the brown wire at the swich that showed  12 volts. when i hit the remote this time, not only did it fail to start it blew parking lights/dash lights out on the van. I havnt changed the brake wire yet, because I dont think this is a problem we are having. This system states any thing that has over 10 amps in the light circut  a relay must be installed and I am thinking the brown wire is just that. When I search data bases for wire diagrams i get conflecting  colors and locations. So I figured I would let the pros hash it out instead of the two guys who have to work together and try and get along

The service manual for that van shows the parking lamp relay control uses a white wire at the BCM at pin B2 on the C4 connector (gray connector)

In the same connector at B5 Lt-Blu wire is door lock control  unlock is B10 white wire  all if you have AU3 option

Horn is B9 Tan on B2 connector 

If BCM is handy  for you  (lower right side of instrument panel) this is where I prefer to tap in---

wow ok there are 2-new ones to add to my growing list of color coded wires for this van. I pulled my sheet and the wire i Used that worked for the parking lights was BROWN / white -  [brown plug pin B2] at the BCM. I am wondering now if my door trigger wire might be wrong? the van has no power locks and no power windows but chevy has done away with the pin switch type door trigger. The wire I used was found in the drivers kick panal and was purple -. I am getting this funny feeling I am going to have several wires serving the 4-doors of this van and am going to have to use diodes to isolate each wire. Any input would help me greatly

thanks much

The driver door trigger is tan in pin B4, the front passenger and rear cargo door trigger is lt. green in pin A5, and the rear doors or sliding doors trigger is yellow/black in pin A10. Use all three wires and diode isolate each.

thats what dei says. they also say p. lights + is brown at fuse box under drivers seat, and - is br/wht at the bcm. the brake wire should be white + trigger. did you doulble check you connection with a meter. i've found purple brake wires that were listed as white in the tech data by more than one source.