Loss of the BUS from the Multipurpose Disk Drive Unit (MDDU) to the CFDIU

TASK 31-32-00-810-936-A
Loss of the BUS from the Multipurpose Disk Drive Unit (MDDU) to the CFDIU

1. Possible Causes

MDDU
wiring

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 31-32-00-740-009	Read the AVIONICS STATUS on the MCDU
ASM 313801
AMM 31-38-22-000-001	Removal of the MDDU
AMM 31-38-22-400-001	Installation of the MDDU

3. Fault Confirmation
Subtask 31-32-00-865-168-A ** ON A/C NOT FOR ALL

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	DATA/LOADER/SPLY	3TD	J16
** ON A/C NOT FOR ALL
121VU	DLS&/DLRB/SPLY	5TD	J15

Subtask 31-32-00-710-063-A ** ON A/C NOT FOR ALL

B. Read the AVIONICS STATUS on the MCDU AMM 31-32-00-740-009.

4. Fault Isolation
Subtask 31-32-00-810-187-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message NO MDDU DATA:

(1) Replace the MDDU AMM 31-38-22-000-001 and AMM 31-38-22-400-001.
(2) If the fault continues:

Do a check and repair the wiring between the MDDU plug connector and the CFDIU (1TW) ASM 313801:
Pin A/24, 25 to pin AA/9F, 9G (1TW).
Pin A/12,13 to pin AA/11F, 11G (1TW).

Subtask 31-32-00-810-187-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message NO MDDU DATA:

(1) Do a check and repair the wiring between the connector (2TD) and the CFDIU (1TW) ASM 313801:

Pin A/24, 25 to pin AA/9F, 9G (1TW).
Pin A/12, 13 to pin AA/11F, 11G (1TW).

Subtask 31-32-00-710-064-A ** ON A/C NOT FOR ALL

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

[Rev.8 from Aug 2018] 2026.04.04 04:29:59 UTC