TM 9-2320-302-20 0010 00-4 Table 1. Electrical System Troubleshooting Procedures - Continued. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Headlight Circuits - Continued 3.  Neither  Headlight  Low/High  Beam  Operates When   Turn   Signal   Switch   Lever   Is   Set   - Continued. 2.    Disconnect    lead    222    from dimmer   switch   lever.   Check for continuity between terminals   of   switch   in   both positions. If continuity is present, go to step 3.  If  continuity  is  not  indicated, replace dimmer switch lever (WP 0073 00). 3.    Disconnect left low/high beam relay  from  connector.  Check for continuity between connector 86 and lead 222. If continuity is present, replace left low/high   beam   relay   (WP 0071 00). If continuity is not indi- cated repair lead 222 (WP 0119 00). 4.  Left/Right Highbeam Does Not Operate. 1.    Inspect headlight bulb. Replace bulb if broken or defective (WP 0083 00). 2.    Disconnect     connector     from left headlight. Check for continuity between ground and connector on left headlight at lead 21/21D. If continuity is present, go to step 3.  If  no  continuity  is  indicated, replace  left  headlight  (WP  0083 00). 3.    Disconnect left low/high beam relay  from  connector.  Check for continuity between lead 21/ 21D and connector 87. If continuity is present, replace left low/high   beam   relay   (WP   0071 00).  If  no  continuity  is  indicated, repair lead 21/21D (WP 0119 00). 5.  Left/Right Lowbeam Does Not Operate. 1.    Inspect headlight bulb. Replace bulb if broken or defective (WP 0083 00). 2.    Disconnect     connector     from left headlight. Check for continuity between ground and    connector    on    left/right headlight at lead 22/22D. If continuity is present, go to step 3.  If  continuity  is  not  indicated, replace  left  headlight  (WP 0083 00). 3.    Disconnect left low/high beam relay  from  connector.  Check for continuity between lead 22/ 22D and connector 87A. If continuity is present, replace left low/high   beam   relay   (WP   0071 00). If continuity is not indicated, repair lead 22/22D (WP 0119 00). Marker and Taillight Circuits 1.  None of Marker and Taillights Operate. 1.    Check tractor tail marker 15A fuse. Replace   fuse   if   defective   (WP 0071 00). 2.    Disconnect connector on vehicular  light  switch.  Install jumper wire between connector  420F  and  pin  F  on switch. Check for +12 VDC at pin H. If +12 VDC is present, repair lead 420H (WP 0119 00). If voltage is not    present    at    vehicular    light switch,    replace    vehicular    light switch (WP 0063 00). 2.  Left/Right    Front    Marker    Light    Does    Not Operate. 1.    Inspect light bulb. Replace bulb if broken or defective (WP 0088 00).