TM 9-2320-363-20-1 Table    3-1. Troubleshooting (Cont) Malfunction Test   or   Inspection Corrective Action 2. NONE OF    THE Step 1. Step   2. Step   3. Step 4. Step    5. 3. ONE OR    MORE Step 1. Step 2. Step    3. ELECTRICAL SYSTEM   (CONT) Blackout Light    Circuits    (Cont) BLACKOUT   (B/O)   STOPLIGHTS OPERATE. Inspect  light   bulbs. . Replace if   broken    or   defective (page 4-216). Disconnect B/O    stoplights 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    connector    421 V    (page    3-2). Check   for   +24 VDC at   connector    85. . If   +24 VDC is   present, go   to   step   4.    If   no   voltage    is   present, repair lead    420N (page    3-2). Check    for   continuity between connector 86    and   ground. . If   continuity is   indicated, go   to   step    5.    If   no   continuity    is indicated, repair    ground    lead    (page 3-2). 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   421  F   (page    3-2). If   no voltage is   present, 4-198). BLACKOUT (B/O) STOPLIGHTS Inspect    light    bulb(s). replace B/O    stoplights    relay    (pages 4-197, NOT OPERATING. . Replace if   broken    or   defective (page    4-216). Remove lamp(s) from    defective circuit(s) (page 4-216). Check    for   continuity between socket and    ground. . If   continuity is   indicated, go   to   step   3.    If   no   continuity    is indicated, replace lamp(s) (page 4-216). Disconnect ground (B/O) stoplight(s). Check for   continuity    between ground lead(s) and    ground. . If   continuity is   indicated, repair    lead(s) 421 F   (page    3-2). If   no continuity is   indicated. repair    around    lead(s) (Page    3-2). 3-38