Stoplight Switch
Disconnect stoplight switch connector (located on brake pedal support). Check continuity between stoplight switch terminals. With brake pedal pressed, continuity should exist between terminals No. 1 and 2, and continuity should not exist between terminals No. 3 and 4. See Fig 1. With brake pedal released, continuity should exist between terminals No. 3 and 4, and continuity should not exist between terminals No. 1 and 2. If continuity is not as specified, replace stoplight switch and retest system operation.