TM 55-1520-240-T
CHAPTER 9
ELECTRICAL SYSTEM TROUBLESHOOTING
CHAPTER OVERVIEW
Chapter 9 contains procedures for Electrical System troubleshooting. Each system and failure symptom is listed below. Included in this chapter are locations and
views of all electrical connectors, receptacles, relays, and ground connections for the Electrical System.
Refer to TM 55-1520-240-23 for required maintenance procedures.
SYSTEM
PARA
DC POWER SYSTEM
9-1
AC POWER SYSTEM
9-2
POSITION LIGHTS
9-3
LANDING (SEARCHLIGHTS)
9-4
FORMATION LIGHTS
9-5
ANTICOLLISION LIGHTS
9-6
MAINTENANCE LIGHTS
9-7
PILOT'S FLIGHT INSTRUMENT PANEL LIGHTS
9-8
SYMPTOM
TASK
ANTICOLLISION LIGHTS DO NOT FLASH, NO. 1 DC SYSTEM
TURNED OFF
9-1.4
ANTICOLLISION LIGHTS DO NOT FLASH, NO. 2 DC SYSTEM
TURNED OFF
9-1.4
BATTERY CHARGING AND CHARGE COMPLETE LIGHTS
OUT
9-1.4
BATTERY CHARGING OR CHARGE COMPLETE LIGHT DOES
NOT COME ON WHEN PRESSED
9-1.4
BATTERY SYSTEM MAL CAPSULE (WITHOUT 74) OR MALF
CAPSULE (WITH 74)ON.
9-1.4
CABIN AND RAMP LIGHTS NOT POWERED FROM SWITCH-
ING BATTERY BUSS
9-1.4
EXTERNAL DC SUPPLY DOES NOT POWER DC BUSSES
9-1.4
EXTERNAL PWR CAPSULE OUT WHEN EXTERNAL DC SUP-
PLY CONNECTED
9-1.4
EXT PWR CONT CIRCUIT BREAKER WILL NOT STAY
CLOSED WITH EXTERNAL POWER APPLIED
9-1.4
MASTER CAUTION LIGHTS DO NOT COME ON WHEN BAT-
TERY SWITCH SET TO ON
9-1.4
RECT 1 AND RECT 2 CAPSULES OUT WHEN EXTERNAL DC
SUPPLY CONNECTED
9-1.4
SYSTEM
PARA
CENTER FLIGHT INSTRUMENT PANEL LIGHTS
9-9
COPILOT'S FLIGHT INSTRUMENT PANEL LIGHTS
9-10
OVERHEAD PANEL LIGHTS
9-11
CONSOLE PANEL LIGHTS
9-12
SECONDARY COCKPIT LIGHTS
9-13
COCKPIT DOME AND UTILITY LIGHTS
9-14
CABIN AND RAMP LIGHTS
9-15
TROOP WARNING SYSTEM
9-16
FAILURE SYMPTOM LIST
DC POWER SYSTEM
SYMPTOM
TASK
NO. 1 AND NO. 2 RECT OFF CAPSULE OUT WHEN EXTER-
NAL DC SUPPLY CONNECTED
9-1.4
RECT 1 OR RECT 2 CAPSULE NOT ON (WITH 74)
9-1.4
NO. 1 OR NO. 2 RECT OFF CAPSULE NOT ON (WITHOUT
74)
9-1.4
RECT 1 CAPSULE ON WHEN APU IS RUNNING (WITH 74)
9-1.4
NO. 1 RECT OFF CAPSULE ON WHEN APU RUNNING
(WITHOUT 74)
9-1.4
RECT 2 CAPSULE ON WHEN APU IS RUNNING (WITH 74)
9-1.4
NO. 2 RECT OFF CAPSULE ON WHEN APU RUNNING
(WITHOUT 74)
9-1.4
OVERHEAD PANEL LIGHTS DO NOT COME ON NO. 1 DC
SYSTEM TURNED OFF
9-1.4
OVERHEAD PANEL LIGHTS DO NOT COME ON, NO. 1 DC
SYSTEM TURNED ON
9-1.4
SWITCHED BATTERY BUS OR ESSENTIAL BUS NOT POW-
ERED BY NO. 1 DC BUS
9-1.4
EXTERNAL POWER CAPSULE NOT ON (EXTERNAL POWER
APPLIED)
9-2.4
SYSTEM
PARA
UTILITY RECEPTACLES
9-17
MASTER CAUTION SYSTEM
9-18
AVIONICS COOLING FAN
9-19
ANTICOLLISION LIGHT (AVIM)
9-20
MASTER CAUTION PANEL (AVIM)
9-21
CLOCK
9-22
CARGO HOOK LIGHTS
9-23
SYMPTOM
TASK
NO. 1 AND NO. 2 RECT OFF CAPSULES ON (EXTERNAL
POWER ON) (WITHOUT 74)
9-2.4
RECT 1 AND RECT 2 CAPSULES ON (EXTERNAL POWER
ON) (WITH 74)
9-2.4
NO. 1 AND NO. 2 RECT OFF CAPSULES ON (NO. 1 GENERA-
TOR SELECTED (WITHOUT 74)
9-2.4
RECT 1 AND RECT 2 CAPSULES ON (NO. 1 GENERATOR SE-
LECTED) (WITH 74)
9-2.4
NO. 1 AND NO. 2 RECT OFF CAPSULES ON (NO. 2 GENERA-
TOR SELECTED) (WITHOUT 74)
9-2.4
RECT 1 AND RECT 2 CAPSULES ON (NO. 2 GENERATOR SE-
LECTED) (WITH 74)
9-2.4
NO. 1 AND NO. 2 RECT OFF CAUTION LIGHTS ON (WITH-
OUT 74)
9-2.4
GEN 1 CAPSULE IS ON (GENERATOR SWITCH ON) (WITH
74)
9-2.4
NO. 1 GENERATOR OFF CAPSULE STAYS ON (GENERATOR
SWITCH IN TEST) (WITHOUT 74)
9-2.4
Change 19 9-2.1
