Loss of the Output B Bus on EIU 1

TASK 73-20-00-810-845-A
Loss of the Output B Bus on EIU 1

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 31-32-00-869-002	Procedure for the Class 3 Fault Reading
AMM 73-21-60-000-001	Removal of the Electronic Control Unit (ECU)
AMM 73-21-60-400-001	Installation of the Electronic Control Unit (ECU)
ASM 732505
ASM 732506
AMM 73-25-34-000-040	Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-400-040	Installation of the Engine Interface Unit (EIU)

3. Fault Confirmation
Subtask 73-20-00-865-058-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
49VU	ENGINE/1/FADEC A/AND EIU 1	2KS1	A04
121VU	ENGINE/ENG1/FADEC B/AND EIU 1	4KS1	R41

Subtask 73-20-00-710-108-A ** ON A/C NOT FOR ALL

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

4. Fault Isolation
Subtask 73-20-00-810-095-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message NO EIU1 DATA:

(1) If there is 28VDC:

(2) If the fault continues:

do a check and repair the wiring from the EIU 1 (1KS1) pins AB/5H, 5K to the first terminal block ASM 732506.

(3) If the fault continues:

Subtask 73-20-00-710-109-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:35:19 UTC