TM  10-3930-638-24&P 2-24.   LIGHT   SYSTEMS   TROUBLESHOOTING   (cont) MALFUNCTION TEST OR INSPECTION CORRECTIVE  ACTION 4. SERVICE TAIL LIGHTS INOPERATIVE NOTE If one service tail light operates normally, replace bulb in affected tail light (para 2-30d). If tail light is still inoperative, check for open circuit in wire between inoperative tail light and operating tail light. Unscrew and remove cable connector from bottom of VEHICLE LIGHTS switch. Place main switch lever on VEHICLE LIGHTS switch in SER. DRIVE  position. Connect ohmmeter leads to pins H and F of VEHICLE LIGHTS switch. a. If ohmmeter indicates more than 0.1 ohm, replace VEHICLE  LIGHTS  switch  (para  2-28b). b. If ohmmeter indicates less than 0.1 ohm, check for open circuit in wire between terminal H of cable connector and service tail lights. 5. BLACK OUT STOP LIGHTS INOPERATIVE NOTE If one stop light operates normally, replace bulb in affected stop light (para 2-30c). If stop light is still inoperative, check for open circuit in wire between  inoperative  stop  light  and  operating  stop  light. Step  1. Place  IGNITION  switch  in  ON  position,  VEHICLE  LIGHTS  switch  in  SER.  DRIVE  position, and depress brake pedal. a.  If  service  brake  lights  operate  normally,  turn  IGNITION  switch  and  VEHICLE  LIGHTS  switch to OFF position and proceed to step 2. b. If service brake lights are inoperative, trouble- shoot stop light switch (para 2-24, MAL- FUNCTION  6). Step 2. Unscrew and remove cable connector from bottom of VEHICLE LIGHTS switch. Place main switch lever on VEHICLE LIGHTS switch in B.O. MARKER  or  B.O.  DRIVE  position. Connect ohmmeter leads to pins A and F of VEHICLE LIGHTS switch and check for less than 0.1 ohm, then connect ohmmeter leads to pins K and N and check for less than 0.1 ohm. a. If ohmmeter indicates more than 0.1 ohm for either test, replace VEHICLE LIGHTS switch (para 2-28b). 2-109