Loss of the BUS 4 Data from the CFDIU to the AMU

TASK 23-51-00-810-846-A
Loss of the BUS 4 Data from the CFDIU to the AMU

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 23-51-00-740-002	BITE Test of the Audio System
AMM 23-51-34-000-001	Removal of the Audio Management Unit (AMU) (1RN)
AMM 23-51-34-400-001	Installation of the Audio Management Unit (AMU) (1RN)
ASM 313205

3. Fault Confirmation
Subtask 23-51-00-865-051-A

A. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	CFDS/CFDIU/SPLY	2TW	J18
121VU	CFDS/CFDIU/BACK/UP	8TW	J17

Subtask 23-51-00-740-094-A

B. Test
Do the BITE test of the Audio System AMM 23-51-00-740-002.

4. Fault Isolation
Subtask 23-51-00-810-095-B

A. If the test gives the maintenance message CFDIU(1TW)/AMU(1RN):

(1) If the fault continues:

Do a check and repair the wiring of the BUS 4 OUTPUT signal from the AMU [1RN] pins AB/15A, 15B to the first terminal block ASM 313205.

Subtask 23-51-00-740-095-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:25:46 UTC