TM 10-3930-664-10 c. Lighting Switches. KEY CONTROL OR INDICATOR FUNCTION 1 Main Lighting Control Switch This  light  switch  has  five  positions.    The  following  lists  the  lights  that  will operate in each position. OFF Position (lever in center position): All lights off, auxiliary switch and stop light switch disabled. BO MARKER Position: Front blackout markers and blackout tail lights lit, stop light switch enabled (blackout stop lights lit when brake pedal applied). BO DRIVE Position: Blackout driving lamp, front blackout marker lights, and blackout tail lights lit, stop light switch enabled (blackout stop lights lit when brake pedal applied).  Back-up alarm and horn will not operate. STOP LIGHT Position: Stop light switch enabled (service stop lights lit when brake pedal applied). SER  DRIVE  Position:  Service  headlights  and  service  tail  lights  lit,  stop  light switch enabled (service stop lights lit when brake pedal applied).  Front and rear flood lights will operate.  Backup alarm enabled. 2-5