TM 1–1520–238–T–3
Change 4
15–7
15–14 SIGNAL NAME:
BIT INITIATE TO TEU (ACY) BIT INT CMD (ACZ)
MEMORY LOCATION: 001246
MEMORY DATA BIT(S):
4
(BINARY)
CONDITION:
(None)
SIGNAL FUNCTION:
Initiates or aborts built–in–test (BIT).
REMARKS: From FCC through LH FAB MRTU Type I to TEU.
PASS:
If sixth digit on HOD is 0, go to paragraph 15–15.
FAIL: Location of fault: LH FAB MRTU Type I, wiring from LH FAB MRTU Type I to TEU, TEU, FCC.
Troubleshoot wiring to isolate fault (TM 1–1270–476–T).
15–15 SIGNAL NAME:
BIT CLASS TO TEU (ACY) BITE CLASS CMD (ACZ)
MEMORY LOCATION: 001246
MEMORY DATA BIT(S):
6
(BINARY)
CONDITION:
(None)
SIGNAL FUNCTION:
Indicates class A (inflight) or B (ground) test after BIT.
REMARKS: From FCC through LH FAB MRTU Type I to TEU.
PASS:
If fifth digit on HOD is 2, 4, 6, or 7, go to paragraph 15–16.
FAIL: Location of fault: LH FAB MRTU Type I, wiring from LH FAB MRTU Type I to TEU, TEU.
Troubleshoot wiring to isolate fault (TM 1–1270–476–T).
15–16 SIGNAL NAME:
BIT ID TO TEU (ACY) BITE ID CMD (ACZ)
MEMORY LOCATION: 001246
MEMORY DATA BIT(S):
5
(BINARY)
CONDITION:
If fifth digit displayed on HOD is 0, 1, 2, or 3=TADS
If fifth digit displayed on HOD is 4, 5, 6, or 7=PNVS
SIGNAL FUNCTION:
Indicates either TADS or PNVS BIT initiation.
REMARKS: From FCC through LH FAB MRTU Type I to TEU.
PASS:
If fifth digit on HOD is 0, 1, 2, or 3, go to paragraph 15–17.
FAIL: Location of fault: LH FAB MRTU Type I, wiring from LH FAB MRTU Type I to TEU, TEU, FCC.
Troubleshoot wiring to isolate fault (TM 1–1270–476–T).
15–17 SIGNAL NAME:
TADS CRITICAL BIT
MEMORY LOCATION: 001076
MEMORY DATA BIT(S):
4
(BINARY)
CONDITION:
(None)
SIGNAL FUNCTION:
Indicates TPS failure.
REMARKS: From TPS through LH FAB MRTU Type I to FCC.
PASS:
If sixth digit on HOD is 1, go to paragraph 15–18.
FAIL: Location of fault: replace TPS (TM 1–1270–476–20).
15–18 SIGNAL NAME:
TADS CRITICAL PWR
MEMORY LOCATION: 001076
MEMORY DATA BIT(S):
5
(BINARY)
CONDITION:
(None)
SIGNAL FUNCTION:
Monitors 5 VDC critical bus.
REMARKS: From TPS through LH FAB MRTU Type I to FCC.
PASS:
If fifth digit on HOD is 4, 5, 6, or 7, refer to failure symptom index and next failure symptom
paragraph.
FAIL: Location of fault: replace TPS (TM 1–1270–476–20).
