03 impala rear defrost wire

i need a wire to hit to trigger the rear defrost on remote start, either at the bcm or the back of the temp controller.

The astrochart shows a white(-)NEG at the harness behind the switch. What is NOT given, is pulse or latched....?

so the harness behind the temp control?? i'm gonna assume it's a pulse as there are only four buttons on the control, and atleast 8wires on the harness, so i'm thinking to rest are for the led on the control.   anyone else know for sure??

not a negative trigger to the white or WHITE/ black, any other idea's??

turns out it is related to the white wire behind the temp control, but it seems the wire has a 12volt feed when the defogger is off, and goes to about 1-2volts when it's on. i can't think of a way to work a relay to turn that one with a negative pulse, or if a pulse will even work (alarm can do a 5min latch, but the cars switch runs it for about 15min, which is much better)

problem solved, ended up soldering a wire to the button switch in the temp control. needs a +12v pulse to trigger the rear defrost. email me if you want pics or need to know how to do it.   defyreality@sonicbliss.ca