Loss of the BSCU Output Bus 2 by the CFDIU

TASK 31-32-00-810-913-A
Loss of the BSCU Output Bus 2 by the CFDIU

1. Possible Causes

CFDIU [1TW]
wiring

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 31-32-00-869-002	Procedure for the Class 3 Fault Reading
ASM 313204
AMM 31-32-34-000-001	Removal of the CFDIU
AMM 31-32-34-400-001	Installation of the CFDIU

3. Fault Confirmation
Subtask 31-32-00-865-154-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	HYDRAULIC/BRAKING AND STEERING/SYS1/CTL	1GG	M34
121VU	HYDRAULIC/BRAKING AND STEERING/SYS1/IND AND/SPLY	2GG	M33

Subtask 31-32-00-740-272-B

B. On the CFDS MENU page, get access to the AVIONICS STATUS page AMM 31-32-00-869-002.

NOTE: If the fault message NO BSCU 1 DATA is triggered after an operational reset of the anti skid and nose wheel steering system with the A/SKID & NOSE WHEEL control switch (5GG):

no action is necessary.

4. Fault Isolation
Subtask 31-32-00-810-163-B

A. If the test gives the maintenance message NO BSCU 1 DATA:

replace the CFDIU [1TW] AMM 31-32-34-000-001 and AMM 31-32-34-400-001.

(1) If the fault continues:

do a check and repair the wiring from the CFDIU (1TW) pins AA/8F, 8G to the first terminal block ASM 313204.

Subtask 31-32-00-740-273-A

B. Do the test given in Para. 3.B.

[Rev.8 from Aug 2018] 2026.04.04 04:29:57 UTC