TM 10-3930-669-20 6.  HOUR METER DOES NOT OPERATE (CONT). KNOWN INFO All 24 vdc circuits operate. POSSIBLE PROBLEMS Wire 5 faulty. Hour meter ground wire faulty. Hour meter faulty. Wire 64 faulty. Alternator faulty. KNOWN INFO All 24 vdc circuits operate. Wire 5 OK. POSSIBLE PROBLEMS Hour meter ground wire faulty. Hour meter faulty. Wire 64 faulty. Alternator faulty. TEST OPTIONS Voltage test. STE/ICE-R #89. REASON FOR QUESTION If 22 to 24 vdc are not present, wire 5 is faulty. TEST OPTIONS Continuity test. STE/ICE-R #91. REASON FOR QUESTION If    continuity    is    not    present, hour     meter     ground     wire     is faulty.      If   hour   meter   ground wire     is     OK,     hour     meter     is faulty. ¬ ¬ 2-156