HORN, Horn Wiring Diagram for GMC Magnavan G3500 1990, List of elements for Horn Wiring Diagram for GMC Magnavan G3500 1990:, interior lights, Fuse block, Horn relay (behind left side of i/p), Horn switch, Horn/dm fuse 20a, Hot at all times, Left horn (left front of radiator support), Nca, Right horn (right front of radiator support), Steering column switches, , , COOLING FAN, STARTING/CHARGING, POWER WINDOWS, HORN, RADIO, POWER DOOR LOCKS, WIPER/WASHER, ,