ELECTRICAL DATA (cont)
f. Circuit Breakers.
Circuit breakers are to be at closed (ON) position. Troubleshooting procedures for all
circuit breakers and all electrical circuits supplying electrical power to circuit breakers are in TM 1-1520-238-T-6.
g. Signal Names, States, Conditions, and Values.
Signal values shown exist for the conditions and
states indicated by signal names.
h. Coaxial Cable Resistance Measurements.
When the ends of a coaxial cable are disconnected,
resistance measurements from the shield to the center conductor should indicate open.
i. Coaxial Connectors.
Triaxial connectors and some coaxial connectors are shown in the wiring diagrams
with two pins (for example: pin 1 and pin 1S). Pin 1 is shown inside Pin 1S with shield attached to pin 1S. For
triaxial connectors, the second shield is attached to the case and is not identified by a pin number or letter.
j. Electrically Operated Devices.
Relays, solenoids, and other electrically activated devices are shown in
the deenergized state in wiring interconnect diagrams.
k. Wiring Information.
(1) Wiring interconnect diagrams are used for wiring checks. Reference designators are shown in the
lower right corner of the LRU on the wiring interconnect diagrams. Electrical wiring repairs peculiar to the
helicopter are in TM 55-1520-238-23. Electrical wiring repairs not peculiar to the helicopter are in
(2) The wiring diagram manual, TM 1-1520-238-T-10, contains the following additional information:
Wiring diagram directory listing reference designator, component name, wire harness and
applicable equipment system.
End view of all connectors.
Wiring harness and routing diagram includes wire harness numbers, exact connectors, terminal
boards, and ground stud locations, etc., found in the helicopter.
l. Wiring Checks.
Where REPAIR OR REPLACE WIRING OR CONNECTIONS are specified:
(1) A check is to be made for a short or open (as specified) for each wire segment, terminal board,
connector pin and connection over the entire length of wiring between pins or terminals indicated.
(2) The wiring interconnect diagram is used to make wiring checks for troubleshooting the equipment.
(3) Instructions to repair wire(s) include repair or replacement of wires, connections at end connector pins,
terminals, etc. (all required endtoend repair and replacement between wiring points specified).
(4) The component location and configuration (ECLC) index is used to locate wiring connectors and
components located in the helicopter.
m. Terminal Board Connections.
Electrical connections at terminal boards are shown as follows (fig. 11):
(1) Vertical and horizontal lines indicate electrical separation between terminals and blocks of terminals.
(2) Absence of lines indicate no separations.