TM 9-2320-363-20-1 Table   3-1. Troubleshooting (Cont) Malfunction Test   or   Inspection Corrective   Action 1. NONE OF    THE Step   1. Step 2. Step    3. PANEL Cheek ELECTRICAL   SYSTEM   (CONT) Panel   Light   Circuits    (Cont) LIGHTS   OPERATING. panel   lights  15A  fuse. . If   defective, replace 15A   fuse   (page   4-204). Disconnect  lead  420B   from   electronic dimmer switch.    Check  for  +12   VDC    at lead   420B from   dimmer    switch. . If   +12    VDC is   present, repair lead    420B (page 3-2). If   no voltage    is   present, go   to   step   3. Disconnect ground    lead   from   dimmer    switch. Check for continuity between ground  lead    and   ground. . If   continuity is indicated, replace electronic dimmer switch (page 4-1 68). If no continuity is indicated, repair ground lead (page 3-2). 2. SHIFTER CONTROL LIGHT NOT    OPERATING, OTHER SHIFTER CIRCUITS OPERATING NORMALLY. Step 1. Check shifter    control   lamp. . If   defective, replace lamp    (page 4-335). Step    2. Check for   continuity    between    socket    and    ground. . If    continuity is indicated, go to step 3. If no continuity is indicated, repair ground lead (page 3-2). Step 3. Disconnect lead 29A from shifter    control    light. Check    for   +12 VDC at lead  29A   from  panel  fuse. . If   +12    VDC    is   present, repair lead 29A to shifter control light. If no voltage is    present, repair lead 29A from 15A fuse    (page    3-2). 3. HEATER CONTROL LIGHT NOT OPERATING, OTHER HEATER CIRCUITS OPERATING NORMALLY. Step 1. Check heater control lamp. . If    defective, replace lamp    (page 4-190). Step    2. Check for   continuity   between socket    and    ground. . If   continuity   is   indicated, go   to   step    3.    If   no   continuity    is indicated, repair   ground    lead    (page 3-2). 3-59