TM 10-3930-669-20 22.  TRANSMISSION DOES NOT OPERATE ON FORWARD OR REVERSE (CONT). KNOWN INFO All 24 vdc circuits operate. Fuse 3 OK. HIGH Range Indicator operates. Master cylinder pressure switch OK. Wire 10B OK. Diode module DM1 OK. POSSIBLE PROBLEMS Wire 10 faulty. Interlock switch faulty. Wire 10A faulty. KNOWN INFO All 24 vdc circuits operate. Fuse 3 OK. HIGH Range Indicator operates. Master cylinder pressure switch OK. Wire 10B OK. Diode module DM1 OK. Wire 10 OK. POSSIBLE PROBLEMS Interlock switch faulty. Wire 10A faulty. TEST OPTIONS Voltage test. STE/ICE-R #89. REASON FOR QUESTION If 22 to 24 vdc are not present, wire 10 is faulty. TEST OPTIONS Continuity test. STE/ICE-R #91. REASON FOR QUESTION If    continuity    is    not    present, interlock   switch   is   faulty.      If interlock    switch    is    OK,    wire 10A is faulty. ¬ ¬ 2-260