DOC AIRBUS | TSM A320FEEC A and B BUS Fault on EIU-1
TASK 73-25-00-810-A62-A
EEC A and B BUS Fault on EIU-1
1. Possible Causes
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Fault Confirmation
Subtask 73-25-00-710-499-A ** ON A/C NOT FOR ALL
Subtask 73-25-00-810-343-A ** ON A/C NOT FOR ALL
Subtask 73-25-00-860-104-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:36:45 UTC
EEC A and B BUS Fault on EIU-1
1. Possible Causes
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | 1 | MULTIMETER - STANDARD |
| No specific | 1 | PLIERS - JAWED, SOFT |
| REFERENCE | DESIGNATION |
|---|---|
| AMM 70-70-00-910-803 | SPOP 6 - Cleaning of the Contact Points and Wiring Harnesses |
| AMM 71-13-00-010-802 | Opening of the Fan Cowl Doors |
| AMM 71-13-00-410-802 | Closing of the Fan Cowl Doors |
| AWM 715135 | |
| AMM 73-21-01-000-801 | Removal of the Electronic Engine Control (EEC) |
| AMM 73-21-01-400-801 | Installation of the Electronic Engine Control (EEC) |
| AMM 73-21-61-000-802 | Removal of the Electronic Engine Control (EEC) Wiring Harness (WF01) |
| AMM 73-21-61-400-802 | Installation of the Electronic Engine Control (EEC) Wiring Harness (WF01) |
| AMM 73-21-62-000-802 | Removal of the EEC Wiring Harness (WF02) |
| AMM 73-21-62-400-802 | Installation of the EEC Wiring Harness (WF02) |
| AWM 732527 | |
| AWM 732529 | |
| 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) |
Subtask 73-25-00-710-499-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 IsolationSubtask 73-25-00-810-343-A ** ON A/C NOT FOR ALL
A. If there is confirmation of the fault:
(1) Check if FADEC 1 CH A fault for 28 VDC FAIL and FADEC 1 CH B fault for 28 VDC FAIL come on.
(a) On the ENG section of maintenance panel 50VU:
1 Release the FADEC GND PWR/1 pushbutton switch (the ON legend comes on).
(b) Check on FADEC 1 CH A and FADEC 1 CH B ground scanning reports if 28 VDC FAIL FAIL comes on, troubleshoot them first.
(2) If 28 VDC FAIL faults do not come on:
(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.
(3) If the fault continues:
(a) Remove EIU-1 [1KS1] AMM 73-25-34-000-802.
(4) Open the fan cowl doors on ENG 1 AMM 71-13-00-010-802.
(5) Use a PLIERS - JAWED, SOFT to disconnect the electrical connectors P402 (402VC1-A) and P403 (403VC1-A) from the pylon junction box.
(6) Use a MULTIMETER - STANDARD to test the EIU-1/402VC1 and EIU-1/403VC1 circuits in the aircraft wiring AWM 732527 and AWM 732529. Refer to Table 1 and Table 2. Look for:
(a) Wire-to-wire shorts
(b) Shorts to ground
(c) Continuity (less than 5 ohms resistance).
Table 1: EIU-1/402VC1 Connector Contacts
Table 1: EIU-1/403VC1 Connector Contacts
(7) If a problem is found:
(a) Repair or replace wiring AWM 732527 and AWM 732529.
(b) Install EIU-1 [1KS1] AMM 73-25-34-400-802.
(c) Connect electrical connector P402 (402VC1-A) and P403 (403VC1-A) to the pylon junction box.
(d) Do the test given in Para. 3.
(8) If no problem is found or if the fault continues, inspect the engine harnesses.
(a) Examine the WF02 (4218KS) harness, connector P1 (4000KS-P1) - EEC (4000KS) and connector P402 (402VC1-A) - pylon junction box and the WF01 (4217KS) harness, connector P2 (4000KS-P2) - EEC (4000KS) and connector P403 (403VC1-A) - pylon junction box, for problems which are possible between the EEC (4000KS) and the pylon junction box.
1 Inspect for harness damage.
2 Inspect for loose or damaged connectors.
a Replace HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
b Replace HARNESS-FAN, WF01 [4217KS] AMM 73-21-61-000-802 and AMM 73-21-61-400-802.
c Do the test given in Para. 3.
(9) If no problems are found with the harness or the fault continues, disconnect the electrical connector P1 (4000KS-P1) from the EEC (4000KS) and connector P402 (402VC1-A) from the pylon junction box and disconnect the electrical connector P2 (4000KS-P2) from the EEC (4000KS) and connector P403 (403VC1-A) from the the pylon junction box.
(a) Examine the pins and sockets (contacts) for alignment and damage. Look for contacts pushed rearward into the connector face. Replace parts as necessary.
(b) Clean the contacts with contact cleaner and clean cloth per SPOP 6. Blow dry with air (at less than 30 psi) across connector face AMM 70-70-00-910-803.
(c) Reconnect the electrical connector P1 (4000KS-P1) to the EEC (4000KS) and connector P402 (402VC1-A) to the pylon junction box.
(d) Reconnect the electrical connector P2 (4000KS-P2) to the EEC (4000KS) and connector P403 (403VC1-A) to the pylon junction box.
(e) Do the test given in Para. 3.
(10) If the fault continues:
(a) Disconnect the electrical connectors P402 (402VC1-A) and P403 (403VC1-A) from the pylon junction box.
(11) Disconnect the electrical connector P1 (4000KS-P1) and the electrical connector P2 (4000KS-P2) from the EEC (4000KS).
(12) Test the P1/402VC1-A and P2/403VC1-A circuits in the harness AWM 715135 sheets 1 and 2. Refer to Table 3 and 4. Look for:
(a) Wire-to-wire shorts
(b) Shorts to ground
(c) Continuity (less than 5 ohms resistance).
Table 3: P1/ 402VC1-A Connector Contacts
Table 4: P2/ 403VC1-A Connector Contacts
(13) If a problem is found:
(a) Replace HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
(b) Replace HARNESS-FAN, WF01 [4217KS] AMM 73-21-61-000-802 and AMM 73-21-61-400-802.
(c) Do the test given in Para. 3.
(14) If no problem is found or if the fault continues:
(a) Replace EEC-1 [4000KS1] AMM 73-21-01-000-801 and AMM 73-21-01-400-801.
(b) Do the test given in Para. 3.
5. Close-up(1) Check if FADEC 1 CH A fault for 28 VDC FAIL and FADEC 1 CH B fault for 28 VDC FAIL come on.
(a) On the ENG section of maintenance panel 50VU:
1 Release the FADEC GND PWR/1 pushbutton switch (the ON legend comes on).
NOTE: After the FADEC is energized, wait ten seconds before you start the test. If you do not wait ten seconds, the interactive mode stops the EEC self-test and this can cause spurious faults.
2 Push the FADEC GND PWR/1 pushbutton switch (the ON legend goes off). (b) Check on FADEC 1 CH A and FADEC 1 CH B ground scanning reports if 28 VDC FAIL FAIL comes on, troubleshoot them first.
(2) If 28 VDC FAIL faults do not come on:
(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.
(3) If the fault continues:
(a) Remove EIU-1 [1KS1] AMM 73-25-34-000-802.
(4) Open the fan cowl doors on ENG 1 AMM 71-13-00-010-802.
(5) Use a PLIERS - JAWED, SOFT to disconnect the electrical connectors P402 (402VC1-A) and P403 (403VC1-A) from the pylon junction box.
(6) Use a MULTIMETER - STANDARD to test the EIU-1/402VC1 and EIU-1/403VC1 circuits in the aircraft wiring AWM 732527 and AWM 732529. Refer to Table 1 and Table 2. Look for:
(a) Wire-to-wire shorts
(b) Shorts to ground
(c) Continuity (less than 5 ohms resistance).
NOTE: A short to ground is found when the resistance is less than 100 000 (100K) ohms.
Table 1: EIU-1/402VC1 Connector Contacts
| (402VC1) Connector AA Contacts | EIU-1 (1KS1) Connector AA Contacts |
|---|---|
| 36 | 11K |
| 18 | 12K |
Table 1: EIU-1/403VC1 Connector Contacts
| (403VC1) Connector AA Contacts | EIU-1 (1KS1) Connector AA Contacts |
|---|---|
| 36 | 14K |
| 18 | 15K |
(a) Repair or replace wiring AWM 732527 and AWM 732529.
(b) Install EIU-1 [1KS1] AMM 73-25-34-400-802.
(c) Connect electrical connector P402 (402VC1-A) and P403 (403VC1-A) to the pylon junction box.
(d) Do the test given in Para. 3.
(8) If no problem is found or if the fault continues, inspect the engine harnesses.
(a) Examine the WF02 (4218KS) harness, connector P1 (4000KS-P1) - EEC (4000KS) and connector P402 (402VC1-A) - pylon junction box and the WF01 (4217KS) harness, connector P2 (4000KS-P2) - EEC (4000KS) and connector P403 (403VC1-A) - pylon junction box, for problems which are possible between the EEC (4000KS) and the pylon junction box.
1 Inspect for harness damage.
2 Inspect for loose or damaged connectors.
NOTE: Loose connectors must be disconnected and examined for further wear or damage.
3 If a problem is found with the harnesses or connectors: a Replace HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
b Replace HARNESS-FAN, WF01 [4217KS] AMM 73-21-61-000-802 and AMM 73-21-61-400-802.
c Do the test given in Para. 3.
(9) If no problems are found with the harness or the fault continues, disconnect the electrical connector P1 (4000KS-P1) from the EEC (4000KS) and connector P402 (402VC1-A) from the pylon junction box and disconnect the electrical connector P2 (4000KS-P2) from the EEC (4000KS) and connector P403 (403VC1-A) from the the pylon junction box.
(a) Examine the pins and sockets (contacts) for alignment and damage. Look for contacts pushed rearward into the connector face. Replace parts as necessary.
(b) Clean the contacts with contact cleaner and clean cloth per SPOP 6. Blow dry with air (at less than 30 psi) across connector face AMM 70-70-00-910-803.
(c) Reconnect the electrical connector P1 (4000KS-P1) to the EEC (4000KS) and connector P402 (402VC1-A) to the pylon junction box.
(d) Reconnect the electrical connector P2 (4000KS-P2) to the EEC (4000KS) and connector P403 (403VC1-A) to the pylon junction box.
(e) Do the test given in Para. 3.
(10) If the fault continues:
(a) Disconnect the electrical connectors P402 (402VC1-A) and P403 (403VC1-A) from the pylon junction box.
(11) Disconnect the electrical connector P1 (4000KS-P1) and the electrical connector P2 (4000KS-P2) from the EEC (4000KS).
(12) Test the P1/402VC1-A and P2/403VC1-A circuits in the harness AWM 715135 sheets 1 and 2. Refer to Table 3 and 4. Look for:
(a) Wire-to-wire shorts
(b) Shorts to ground
(c) Continuity (less than 5 ohms resistance).
NOTE: A short to ground is found when the resistance is less than 100 000 (100K) ohms.
Table 3: P1/ 402VC1-A Connector Contacts
| (402VC1-A) Connector AA Contacts | P1 Connector AA Contacts |
|---|---|
| 36 | c |
| 18 | B |
Table 4: P2/ 403VC1-A Connector Contacts
| (403VC1-A) Connector AA Contacts | P2 Connector AA Contacts |
|---|---|
| 36 | c |
| 18 | B |
(a) Replace HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
(b) Replace HARNESS-FAN, WF01 [4217KS] AMM 73-21-61-000-802 and AMM 73-21-61-400-802.
(c) Do the test given in Para. 3.
(14) If no problem is found or if the fault continues:
(a) Replace EEC-1 [4000KS1] AMM 73-21-01-000-801 and AMM 73-21-01-400-801.
(b) Do the test given in Para. 3.
Subtask 73-25-00-860-104-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.
(a) Close the fan cowl doors AMM 71-13-00-410-802.
(1) Make sure that the work area is clean and clear of tools and other items.
(a) Close the fan cowl doors AMM 71-13-00-410-802.