ACSC Primary and Secondary BUSES Fault on EIU-1

TASK 73-25-00-810-C68-A
ACSC Primary and Secondary BUSES Fault on EIU-1

1. Possible Causes

EIU-1 [1KS1]
CONT-AIR COND SYSTEM 1 [47HH]
CONT-AIR COND SYSTEM 2 [57HH]
wiring

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	MULTIMETER - STANDARD

B. Referenced Information

REFERENCE	DESIGNATION
AWM 216105
AWM 216110
AMM 21-61-34-000-002	Removal of the Air-Conditioning System Controller
AMM 21-61-34-400-002	Installation of the Air-Conditioning System Controller
AWM 732519
AMM 73-25-34-000-802	Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-400-802	Installation of the Engine Interface Unit (EIU)
AMM 73-25-34-710-802	Operational Test of the Engine Interface Unit (EIU) with the Centralized Fault Display System (CFDS)

3. Fault Confirmation
Subtask 73-25-00-710-717-A ** ON A/C NOT FOR ALL

A. Do the operational test of the Engine Interface Unit (EIU) with the Centralized Fault Display System (CFDS) to confirm this fault AMM 73-25-34-710-802.

4. Fault Isolation
Subtask 73-25-00-810-669-A ** ON A/C NOT FOR ALL

A. If there is confirmation of the fault:
(1) Remove EIU-1 [1KS1] AMM 73-25-34-000-802.
(2) Remove CONT-AIR COND SYSTEM 1 [47HH] and CONT-AIR COND SYSTEM 2 [57HH] AMM 21-61-34-000-002.
(3) Use a MULTIMETER - STANDARD to do a test of the EIU/ACSC 1 and the EIU/ACSC 2 circuits in the harness AWM 216105, AWM 216110 and AWM 732519. Refer to Table 1 and Table 2. Look for:

Wire-to-wire shorts
Shorts to ground
Continuity (less than 5 ohms resistance).

NOTE: A short to ground is found when the resistance is less than 100 000 (100K).

Table 1: EIU/ACSC 1 Connector Contacts

ACSC 1 (47HH) Connector AA Contacts	EIU-1 (1KS1) Connector AA Contacts
7E	2J
7F	2K

Table 2: EIU/ACSC 2 Connector Contacts

ACSC 2 (57HH) Connector AA Contacts	EIU-1 (1KS1) Connector AA Contacts
7E	3J
7F	3K

(4) If a problem is found:
(a) Repair or replace wiring AWM 216105, AWM 216110 and AWM 732519.
(b) Install EIU-1 (1KS1) AMM 73-25-34-400-802.
(c) Install CONT-AIR COND SYSTEM 1 (47HH) and CONT-AIR COND SYSTEM 2 (57HH) AMM 21-61-34-400-002.
(d) Do the test given in Para. 3.
(5) If no problem is found or if fault continues:
(a) Replace CONT-AIR COND SYSTEM 1 [47HH] and CONT-AIR COND SYSTEM 2 [57HH] AMM 21-61-34-000-002 and AMM 21-61-34-400-002.
(b) Do the test given in Para. 3.
(6) If no problem is found or if fault continues:
(a) Replace EIU-1 [1KS1] AMM 73-25-34-000-802 and AMM 73-25-34-400-802.
(b) Do the test given in Para. 3.

5. Close-up
Subtask 73-25-00-860-314-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.
(1) Make sure that the work area is clean and clear of tools and other items.

[Rev.8 from Aug 2018] 2026.04.04 04:36:56 UTC