GMC Sierra 3500 (2002-2006) Rear defogger circuit

BLK WIRE BODY CONTROL MODULE (ON LOWER LEFT SIDE OF DASH) COMPUTER DATA LINES SYSTEM HOT AT ALL TIMES HOT IN RUN, START HTR HVAC CONTROL MODULE (IN CENTER OF DASH) I/P RELAY BLOCK (NEAR LEFT KICK PANEL) IGN LOGIC LT GRN WIRE PPL REAR DEFOG SWITCH REAR DEFOGGER RELAY REAR WINDOW DEFOGGER GRID RELAY CNTRL SERIAL DATA WHT WIRE