TM 10-3930-669-20 19.  GLOW PLUG INDICATOR DOES NOT OPERATE (CONT). KNOWN INFO 24 vdc circuits operate. Fuse 4 OK. Indicator wire 30 OK. Relay R6 ground wire OK. Indicator ground wire OK. Wire 31 OK. Terminal 85 ground wire OK. POSSIBLE PROBLEMS Relay R6, wire 7, terminal 30 faulty. Relay R6, wire 30, terminal 87 faulty. Wire 7 faulty. Wire 29 faulty. Glow plug switch faulty. KNOWN INFO 24 vdc circuits operate. Fuse 4 OK. Indicator wire 30 OK. Relay R6 ground wire OK. Indicator ground wire OK. Wire 31 OK. Terminal 85 ground wire OK. Relay R6, wire 7, terminal 30 OK. Wire 7 OK. POSSIBLE PROBLEMS Relay R6, wire 30, terminal 87 faulty. Wire 29 faulty. Glow plug switch faulty. TEST OPTIONS Voltage test. STE/ICE-R #89. REASON FOR QUESTION If 22 to 24 is not present, wire 7 is faulty. TEST OPTIONS Continuity test. STE/ICE-R #91. REASON FOR QUESTION If continuity is not present, wire 30 is faulty.  If wire 30 is OK, relay R6 is faulty. 2-238