ELECTRICAL SYSTEM KEY DESCRIPTION KEY DESCRIPTION 1 - REVERSE WARNING ALARM 43 - HORN SWITCH 2 - REVERSE WARNING HARNESS 44 - HARNESS 3 - REAR WORK LIGHT [04B20] ELECTRICAL SYSTEM 9015 670A, 672A, and 670A, 672A (Automatic Blade Control System) Graders PC1620 in GRADER, MOTOR 672A