TM 9-2320-302-20 0010 00-12 Table 1. Electrical System Troubleshooting Procedures - Continued. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Utility Light Circuits - Continued 1.  Utility Lights Do Not Operate - Continued. 3.    Check  for  +12  VDC  at  lead 420JD    from    auxiliary    light power bus. If +12 VDC is present, go to step 4. If voltage is not present, repair lead 420JD (WP 0119 00). 4.    Disconnect lead 73 from utility light   switch.   Check   for   +12 VDC at lead 73. If +12 VDC is present, go to step 5. If voltage is not present, repair lead 73 (WP 0119 00). 5.    Disconnect    lead    73B    from utility   light   switch.   Activate switch.  Check  for  continuity between switch contacts. If  continuity  is  indicated,  repair lead     73B     (WP     0119     00).     If continuity is not indicated, replace utility light switch (WP 0064 00). 2.  Only One Utility Light Operates. 1.    Disconnect    lead    73B    from defective  utility  light.  Check for +12 VDC at lead 73B. If +12 VDC is present, go to step 2. If voltage is not present, repair lead 73B (WP 0119 00). 2.    Check  for  continuity  between socket and ground. If continuity is indicated, replace utility    light    (WP    0090    00).    If continuity is not indicated, repair ground lead (WP 0119 00). 3.  Utility Light Indicator Light Does Not Operate, But Utility Lights Operate Normally. Disconnect   lead   73A   from   pin D16  of  warning  light  bar.  Check for +12 VDC at lead 73A. If +12 VDC is present, troubleshoot warning light circuit. If   voltage   is   not   present,   repair lead 73A (WP 0119 00). Electric Horn Circuits Electric Horn Does Not Operate. 1.    Check horn 15A fuse. Replace 15A fuse if defective (WP 0071 00). 2.    Check  for  +12  VDC  at  lead 420JD    from    auxiliary    light power bus. If +12 VDC is present, go to step 3. If voltage is not present, repair lead 420JD (WP 0119 00). 3.    Disconnect   horn   relay   from connector.     Check     for     +12 VDC at connector 30. If +12 VDC is present, go to step 4. If voltage is not present, repair lead 24 (WP 0119 00). 4.    Disconnect horn relay. Check for +12 VDC at connector 85. If +12 VDC is present, go to step 5. If voltage is not present, repair lead 24 (WP 0119 00). 5.    Disconnect lead 25 from horn button. Check for +12 VDC at lead 25. If +12 VDC is present, go to step 6. If voltage is not present, replace horn relay (WP 0071 00). 6.    Disconnect  ground  lead  from horn button. Check for continuity between ground lead and ground. If  continuity  is  indicated,  go  to step 7. If continuity is not indicated, repair ground lead (WP 0119 00). 7.    Disconnect lead 25 from horn button.     Press     horn     switch. Check  for  continuity  between switch contacts. If  continuity  is  indicated,  go  to step 8. If continuity is not indicated,     replace     horn     button (WP 0112 00).