TM 9-2320-302-20 0010 00-6 Table 1. Electrical System Troubleshooting Procedures - Continued. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Blackout Light Circuits - Continued 2.  None  of  Blackout  (B/O)  Stoplights  Operate  - Continued. 5.    Install  jumper  wires  between connector   30   and   stoplights relay, connector 85 and stoplights relay, and connector 86 and stoplights relay. Check for    +24    VDC    at    stoplights relay contact 87. If +24 VDC is present, repair lead 421F (WP 0119 00). If voltage is not present, replace B/O stoplights relay (WP 0071 00). 3.  One or None of Blackout (B/O) Marker Lights Operate. 1.    Inspect light bulbs. Replace bulbs if broken or defective (WP 0085 00). 2.    Disconnect B/O marker lights relay  from  connector.  Check for +24 VDC at connector 30. If +24 VDC is present, go to step 3.  If  no  voltage  is  present,  repair lead 421V (WP 0119 00). 3.    Check for +24 VDC at connector 85. If +24 VDC is present, go to step 4. If voltage is not present, repair lead 420E (WP 0119 00). 4.    Check  for  continuity  between connector 86 and ground. If  continuity  is  indicated,  go  to step 5. If continuity is not indicated, repair ground lead (WP 0119 00). 5.    Install  jumper  wires  between connector   30   and   stoplights relay, connector 85 and stoplights relay, and connector 86 and stoplights relay. Check for    +24    VDC    at    stoplights relay contact 87. If +24 VDC is present, repair lead 421A (WP 0119 00). If voltage is not  present,  replace  B/O  marker lights relay (WP 0071 00). 4.  One  or  None  of  Blackout  (B/O)  Drive  Lights Operate. 1.    Inspect light bulbs. Replace bulbs if broken or defective (WP 0084 00). 2.    Disconnect   B/O   drive   lights relay  from  connector.  Check for +24 VDC at connector 30. If +24 VDC is present, go to step 3. If voltage is not present, repair lead 421V (WP 0119 00). 3.    Check for +24 VDC at connector 85. If +24 VDC is present, go to step 4. If voltage is not present, repair lead 420D (WP 0119 00). 4.    Check  for  continuity  between connector 86 and ground. If  continuity  is  indicated,  go  to step 5. If continuity is not indicated, repair ground lead (WP 0119 00). 5.    Install  jumper  wires  between connector   30   and   stoplights relay, connector 85 and stoplights relay, and connector 86 and stoplights relay. Check for    +24    VDC    at    stoplights relay contact 87. If +24 VDC is present, repair lead 421P or lead 421K (WP 0119 00). If voltage is not present, replace B/ O drive lights relay (WP 0071 00).