1999 GMC Sonoma Owner's Manual - Page 304

yellowblue Name B/U LP A/C W/W PMP HORN IGN B RAP LD LEV OXYSEN IGN E MIR/LKS FOG LP IGN A STUD #2 PARKLP LR PRK Usage Back-Up Lamps Air Conditioning Not Used Horn Column Feed, IGN 2, 3, 4 Retained Accessory Power Not Used Oxygen Sensor Engine Mirrors, Door Locks Fog Lamps Starting and Charging IGN 1 Accessory Feeds, Electric Brake Parking Lamps Left Rear Parking Lamps HTDSEAT HVAC TRCHMSL RRDFOG TBC CRANK HAZLP VECHMSL HTDMIR ATC STOPLP RR W/W Name IGN C Usage Starter Solenoid, Fuel Pump, PRNDL Not Used HVAC System Not Used Not Used Truck Body Computer Clutch Switch, NSBU Switch Hazard Lamps Vehicle Center High-Mounted Stoplamp Heated Outside Mirrors Transfer Case (Four-Wheel Drive) Stoplamps Not Used 6-66