TM 9-2320-364-20-3 2-2930 6.  FAN SPEED DOES NOT LOWER FROM HIGH SPEED TO LOW SPEED (CONT). 14. Repair wire 1956 (see schematic Fig 2-67) or notify DS Maintenance.   Verify repair, go to Step 19 of this Fault. YES NO Heater blower motor operates,   indicating CB15 OK. Fan operates at low speed with   hydraulic selector switch in   AUTO or CRANE/SRW   position. Fan speed does not lower with   throttle position switch   depressed. Wire 1956 faulty. Throttle position switch faulty. Wire 1957 faulty. Turbo boost pressure switch   faulty. Wire 1955 faulty. KNOWN INFO POSSIBLE PROBLEMS TEST OPTIONS REASON FOR QUESTION Voltage test. STE/ICE-R #89. If wire 1956 is loose, faulty, or shorted to ground, 22 to 28 vdc will not be present at throttle position switch. 15. Go to Step 18 of this Fault. YES NO Heater blower motor operates,   indicating CB15 OK. Fan operates at low speed with   hydraulic selector switch in   AUTO or CRANE/SRW   position. Fan speed does not lower with   throttle position switch   depressed. Wire 1956 OK. Throttle position switch faulty. Wire 1957 faulty. Turbo boost pressure switch   faulty. Wire 1955 faulty. KNOWN INFO POSSIBLE PROBLEMS TEST OPTIONS REASON FOR QUESTION Continuity test. STE/ICE-R #91. If throttle position switch is not adjusted correctly or is faulty, voltage will not be input to turbo boost pressure switch. WARNING Are 22 to 28 vdc measured on connector MC127, terminal A with engine switch ON? Is continuity measured between throttle position switch connector, terminal A and B? Read   WARNING on Page 2-2931