DOC AIRBUS | TSM A320FEIU Bus Data Failure (single channel ChA)
TASK 73-21-00-810-884-A
EIU Bus Data Failure (single channel ChA)
1. Possible Causes
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Fault Confirmation
Subtask 73-21-00-710-137-A ** ON A/C NOT FOR ALL
Subtask 73-21-00-860-076-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:36:40 UTC
EIU Bus Data Failure (single channel ChA)
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 |
|---|---|
| TSM TASK 71-00-00-810-834-A | General Troubleshooting Guidelines for Additional Troubleshooting Information |
| TSM TASK 71-00-00-810-835-A | Component and Harness Intermittent Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults |
| AMM 24-41-00-861-002 | Energize the Aircraft Electrical Circuits from the External Power |
| AMM 70-70-00-910-803 | SPOP 6 - Cleaning of the Contact Points and Wiring Harnesses |
| 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 73-21-62-000-802 | Removal of the EEC Wiring Harness (WF02) |
| AMM 73-21-62-400-802 | Installation of the EEC Wiring Harness (WF02) |
| AWM 732524 | |
| AWM 732525 | |
| 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 78-36-00-010-802 | Opening of the Thrust Reverser Cowl-Doors |
| AMM 78-36-00-410-802 | Closing of the Thrust Reverser Cowl-Doors |
EEC Wiring HarnessesSubtask 73-21-00-710-137-A ** ON A/C NOT FOR ALL
A. Energize the FADEC of the engine that has the fault report.
(1) Energize the aircraft electrical circuits AMM 24-41-00-861-002.
(2) On the ENG section of maintenance panel 50VU:
(a) Release the FADEC GND PWR/1(2) pushbutton swith (the ON legend comes on).
(4) Push the FADEC GND PWR/1(2) pushbutton switch (the ON legend comes on).
(a) If no problems are found, return the engine to service. Monitor the engine for reoccurring maintenance message.
(6) If the maintenance message comes back (hard fault), perform troubleshooting in the next step.
4. Fault Isolation(1) Energize the aircraft electrical circuits AMM 24-41-00-861-002.
(2) On the ENG section of maintenance panel 50VU:
(a) Release the FADEC GND PWR/1(2) pushbutton swith (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.
(3) On MCDU screen, make sure that the fault is not displayed on ground scanning report. (4) Push the FADEC GND PWR/1(2) pushbutton switch (the ON legend comes on).
NOTE: The Electronic Engine Control (EEC) channel A has detected the Engine Interface Unit (EIU) circuit has failed. The EEC is located on the fan case at the 2 o'clock position.
(5) If the maintenance message does not come back, examine the harness and electrical connectors as described in the component and harness intermittent fault isolation procedure (Ref. TSM TASK 71-00-00-810-835). - Refer to the general troubleshooting guidelines for additional troubleshooting information (Ref. TSM TASK 71-00-00-810-834).
- Refer to the component and harness intermittent troubleshooting procedure for guidance troubleshooting intermittent faults (Ref. TSM TASK 71-00-00-810-835).
(a) If no problems are found, return the engine to service. Monitor the engine for reoccurring maintenance message.
(6) If the maintenance message comes back (hard fault), perform troubleshooting in the next step.
WARNING:
BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.
WARNING:
REFER TO THE MSDS FOR ALL MATERIAL USED AND THE MANUFACTURER'S SAFETY INSTRUCTIONS FOR ALL EQUIPMENT USED. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.
CAUTION:
MAKE SURE YOU REMOVE ELECTRICAL POWER FROM THE EEC BEFORE YOU REMOVE THE ELECTRICAL CONNECTORS. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE EEC CAN OCCUR.
Subtask 73-21-00-810-156-A ** ON A/C NOT FOR ALL A. If there is confirmation of the fault:
(1) Open the thrust reverser cowl-doors AMM 78-36-00-010-802.
(2) Examine the WF02 (4218KS) harness, connector P1 (4000KS-P1) - EEC (4000KS), and connector P402 (402VC-A) - pylon junction box, for problems which are possible between the EEC (4000KS) and the pylon junction box.
(a) Inspect for harness damage.
(b) Inspect for loose or damaged connectors.
1 Replace the HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
2 Do the test given in Para. 3.
(3) If no problems are found with the harness or the fault continues, use a PLIERS - JAWED, SOFT to disconnect the electrical connector P1 (4000KS-P1) from the EEC (4000KS) and connector P402 (402VC-A) from 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 (402VC-A) to the pylon junction box.
(d) Do the test given in Para. 3.
(4) If the fault continues:
(a) Disconnect the electrical connector P1 (4000KS-P1) from the EEC (4000KS) and connector P402 (402VC-A) from the pylon junction box. Use a MULTIMETER - STANDARD to test the EIU circuit in the harness. Refer to Table 1. Look for:
1 Wire-to-wire shorts
2 Shorts to ground
3 Continuity (less than 5 ohms resistance).
(b) If a problem is found with the harness or connectors:
1 Replace the HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
2 Do the test given in Para. 3.
(5) If no problems are found with the harness or the fault continues, do a check of the EIU circuit in the aircraft wiring.
(a) Remove the EIU1 for fault on engine 1 or remove the EIU2 for fault on engine 2 AMM 73-25-34-000-802.
(b) Test the aircraft harness:
1 Wire to wire shorts
2 Shorts to ground
(c) If a problem is found with the harness or connector, repair or replace the harness:
(6) If no problems were found with the harness or the fault continues:
(a) Replace EIU-1 [1KS1] AMM 73-25-34-000-802 and AMM 73-25-34-400-802, or
(b) Replace EIU-2 [1KS2] AMM 73-25-34-000-802 and AMM 73-25-34-400-802.
(c) Do the test given in Para. 3.
(7) If the fault continues:
(a) Replace
(b) Do the test given in Para. 3.
5. Close-up(1) Open the thrust reverser cowl-doors AMM 78-36-00-010-802.
(2) Examine the WF02 (4218KS) harness, connector P1 (4000KS-P1) - EEC (4000KS), and connector P402 (402VC-A) - pylon junction box, for problems which are possible between the EEC (4000KS) and the pylon junction box.
(a) Inspect for harness damage.
(b) Inspect for loose or damaged connectors.
NOTE: Loose connectors must be disconnected and examined for further wear or damage.
(c) If a problem is found with the harness or connectors: 1 Replace the HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
2 Do the test given in Para. 3.
(3) If no problems are found with the harness or the fault continues, use a PLIERS - JAWED, SOFT to disconnect the electrical connector P1 (4000KS-P1) from the EEC (4000KS) and connector P402 (402VC-A) from 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 (402VC-A) to the pylon junction box.
(d) Do the test given in Para. 3.
(4) If the fault continues:
(a) Disconnect the electrical connector P1 (4000KS-P1) from the EEC (4000KS) and connector P402 (402VC-A) from the pylon junction box. Use a MULTIMETER - STANDARD to test the EIU circuit in the harness. Refer to Table 1. Look for:
1 Wire-to-wire shorts
2 Shorts to ground
3 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: EEC to Pylon Junction Box EIU Circuit Channel A Connector Contacts | WF02 (4218KS) Harness P1 (4000KS-P1) EEC (4000KS) Connector Contacts | WF02 (4218KS) Harness P402 (402VC-A) Pylon Junction Box Connector Contacts |
|---|---|
| GG | 4 |
| HH | 12 |
1 Replace the HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
2 Do the test given in Para. 3.
(5) If no problems are found with the harness or the fault continues, do a check of the EIU circuit in the aircraft wiring.
(a) Remove the EIU1 for fault on engine 1 or remove the EIU2 for fault on engine 2 AMM 73-25-34-000-802.
(b) Test the aircraft harness:
1 Wire to wire shorts
2 Shorts to ground
NOTE: Short to ground is found when the resistance is less than 100 000 (100K) ohms.
3 Continuity (less than 5 ohms resistance) NOTE: For continuity, add a jumper between P402 (402VC-A) pins 4 and 12 and check continuity between EIU connector AB pins 5A and 5C.
Table 2: Pylon Junction Box to EIU Connector Contact (Channel A) | P402 (402VC-A) Pylon Junction Box Connector Contacts | On Rack Side EIU Connector Contact |
|---|---|
| 4 | 5A |
| 12 | 5C |
- For engine 1 refer to AWM 732525
- For engine 2 refer to AWM 732524.
(6) If no problems were found with the harness or the fault continues:
(a) Replace EIU-1 [1KS1] AMM 73-25-34-000-802 and AMM 73-25-34-400-802, or
(b) Replace EIU-2 [1KS2] AMM 73-25-34-000-802 and AMM 73-25-34-400-802.
(c) Do the test given in Para. 3.
(7) If the fault continues:
(a) Replace
(b) Do the test given in Para. 3.
Subtask 73-21-00-860-076-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 thrust reverser cowl-doors AMM 78-36-00-410-802.
(1) Make sure that the work area is clean and clear of tools and other items.
(a) Close the thrust reverser cowl-doors AMM 78-36-00-410-802.