DOC AIRBUS | TSM A320FTR DCV 28 VDC Not Available on Channel B
TASK 73-25-00-810-A37-A
TR DCV 28 VDC Not Available on Channel B
1. Possible Causes
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Fault Confirmation
Subtask 73-25-00-710-474-A ** ON A/C NOT FOR ALL
Subtask 73-25-00-860-081-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:36:28 UTC
TR DCV 28 VDC Not Available on Channel B
1. Possible Causes
- EEC WIRING HARNESS WF07 [4093KS]
- aircraft wiring
- HCU-T/R, ENG1 [4310EG1]
- HCU-T/R, ENG2 [4310EG2]
[4000KS]
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 71-13-00-010-802 | Opening of the Fan Cowl Doors |
| AMM 71-13-00-410-802 | Closing of the Fan Cowl Doors |
| AWM 715136 | |
| AWM 715179 | |
| 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 73-21-67-000-801 | Removal of the Electronic Engine Control (EEC) Wiring Harness (WF07) |
| AMM 73-21-67-400-801 | Installation of the Electronic Engine Control (EEC) Wiring Harness (WF07) |
| AMM 73-25-34-710-802 | Operational Test of the Engine Interface Unit (EIU) with the Centralized Fault Display System (CFDS) |
| AMM 78-31-00-710-805 | Operational Test of Thrust Reverser with MCDU |
| AMM 78-31-01-000-801 | Removal of the TRAS Hydraulic Control Unit (HCU) |
| AMM 78-31-01-400-801 | Installation of the TRAS Hydraulic Control Unit (HCU) |
| AWM 783606 | |
| AWM 783607 |
Subtask 73-25-00-710-474-A ** ON A/C NOT FOR ALL
A. Do the operational test of thrust reverser to confirm this fault AMM 78-31-00-710-805.
(a) If no problems are found, return the engine to service. Monitor the engine for reoccurring maintenance message.
(2) If the maintenance message comes back (hard fault), go to the Para. Fault Isolation.
4. Fault IsolationNOTE: The Electronic Engine Control (EEC) has detected no TR DCV 28 VDC for channel B when commanded.
(1) 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.
(2) If the maintenance message comes back (hard fault), go to the Para. Fault Isolation.
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 73-25-00-810-314-A ** ON A/C NOT FOR ALL A. If there is confirmation of the fault:
(1) Do the operational test of the Engine Interface Unit (EIU) with the Centralized Fault Display System (CFDS) AMM 73-25-34-710-802.
(a) Test EIU-1 for fault on ENG 1.
(b) Test EIU-2 for fault on ENG 2.
(2) If the REVERSER POWER SUPPLY RELAY FAULT and/or DCV B SUPPLY FAULT fault message(s) is (are) shown.
(a) Do the related troubleshooting procedure.
(b) Do the test given in Para. 3.
(3) If no messages come on or the fault continues:
(a) Open the fan cowl doors AMM 71-13-00-010-802.
(4) Examine the WF07 (4093KS) harness, connector P8 (4000KS-P8) - EEC (4000KS) and connector P494 (494VC-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 EEC WIRING HARNESS WF07 [4093KS] AMM 73-21-67-000-801 and AMM 73-21-67-400-801.
2 Do the test given in Para. 3.
(5) If no problems are found with the harness, use a PLIERS - JAWED, SOFT to disconnect the electrical connector P8 (4000KS-P8) from the EEC (4000KS) and connector P494 (494VC-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) Reconnect the electrical connector P8 (4000KS-P8) to the EEC (4000KS) and connector P494 (494VC-A) to the pylon junction box.
(c) Do the test given in Para. 3.
(6) If the fault continues:
(a) Disconnect the electrical connector P8 (4000KS-P8) from the EEC (4000KS) and connector P494 (494VC-A) from the pylon junction box. Use a MULTIMETER - STANDARD to test the aircraft 28 VDC circuit in the harness. Refer to Table 1 and AWM 715136 P0002. Look for:
1 Continuity (less than 5 ohms resistance)
2 Wire-to-wire short
3 Short to ground.
Table 1: Aircraft 28 VDC Channel B Connector Contacts
(b) If a problem is found with the harness or connectors:
1 Replace EEC WIRING HARNESS WF07 [4093KS] AMM 73-21-67-000-801 and AMM 73-21-67-400-801.
2 Do the test given in Para. 3.
(7) If no problems with the harness are found or the fault continues:
(a) Check for correct engagement of connector (4310EG-A) AMM 78-31-01-400-801.
1 Correct as necessary.
2 Connect all connectors disconnected.
3 Do the test given in Para. 3.
(b) If no damage found or the fault continue, disconnect connector (4310EG-A):
1 Examine the pins and sockets (contacts) for alignment and damage. Look for contacts pushed rearward into the connector face. Replace parts as necessary.
2 Do the test given in Para. 3.
(c) Check the aircraft wiring for AWM 715179 P0002 and AWM 783606 for ENG 1 fault and AWM 783607 for ENG 2 fault. Look for:
1 Continuity (less than 5 ohms resistance)
2 Wire-to-wire short
3 Short to ground.
and
(d) Repair or replace the aircraft wiring if necessary.
1 Connect all connectors disconnected.
2 Do the test given in Para. 3.
(8) If no problems with the aircraft wiring are found or the fault continues:
(a) Replace HCU-T/R, ENG1 [4310EG1] or HCU-T/R, ENG2 [4310EG2] AMM 78-31-01-000-801 and AMM 78-31-01-400-801.
(b) Do the test given in Para. 3.
(9) If the fault continues:
(a) Replace
(b) Do the test given in Para. 3.
5. Close-up(1) Do the operational test of the Engine Interface Unit (EIU) with the Centralized Fault Display System (CFDS) AMM 73-25-34-710-802.
(a) Test EIU-1 for fault on ENG 1.
(b) Test EIU-2 for fault on ENG 2.
(2) If the REVERSER POWER SUPPLY RELAY FAULT and/or DCV B SUPPLY FAULT fault message(s) is (are) shown.
(a) Do the related troubleshooting procedure.
(b) Do the test given in Para. 3.
(3) If no messages come on or the fault continues:
(a) Open the fan cowl doors AMM 71-13-00-010-802.
(4) Examine the WF07 (4093KS) harness, connector P8 (4000KS-P8) - EEC (4000KS) and connector P494 (494VC-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 EEC WIRING HARNESS WF07 [4093KS] AMM 73-21-67-000-801 and AMM 73-21-67-400-801.
2 Do the test given in Para. 3.
(5) If no problems are found with the harness, use a PLIERS - JAWED, SOFT to disconnect the electrical connector P8 (4000KS-P8) from the EEC (4000KS) and connector P494 (494VC-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) Reconnect the electrical connector P8 (4000KS-P8) to the EEC (4000KS) and connector P494 (494VC-A) to the pylon junction box.
(c) Do the test given in Para. 3.
(6) If the fault continues:
(a) Disconnect the electrical connector P8 (4000KS-P8) from the EEC (4000KS) and connector P494 (494VC-A) from the pylon junction box. Use a MULTIMETER - STANDARD to test the aircraft 28 VDC circuit in the harness. Refer to Table 1 and AWM 715136 P0002. Look for:
1 Continuity (less than 5 ohms resistance)
2 Wire-to-wire short
3 Short to ground.
NOTE: A short to ground is found when the resistance is less than 100 000 (100K)
Table 1: Aircraft 28 VDC Channel B Connector Contacts
| WF07 (4093KS) Harness P8(4000KS-P8) EEC (4000KS) Connector Contacts | WF07 (4093KS) Harness P494(494VC-A) Connector Contacts |
|---|---|
| A | 5 |
| B | 33 |
1 Replace EEC WIRING HARNESS WF07 [4093KS] AMM 73-21-67-000-801 and AMM 73-21-67-400-801.
2 Do the test given in Para. 3.
(7) If no problems with the harness are found or the fault continues:
(a) Check for correct engagement of connector (4310EG-A) AMM 78-31-01-400-801.
1 Correct as necessary.
2 Connect all connectors disconnected.
3 Do the test given in Para. 3.
(b) If no damage found or the fault continue, disconnect connector (4310EG-A):
1 Examine the pins and sockets (contacts) for alignment and damage. Look for contacts pushed rearward into the connector face. Replace parts as necessary.
2 Do the test given in Para. 3.
(c) Check the aircraft wiring for AWM 715179 P0002 and AWM 783606 for ENG 1 fault and AWM 783607 for ENG 2 fault. Look for:
1 Continuity (less than 5 ohms resistance)
2 Wire-to-wire short
3 Short to ground.
NOTE: A short to ground is found when the resistance is less than 100 000 (100K)
| HCU (4310EG-A) Connector Contacts | (494VC) Connector Contacts |
|---|---|
| 4 | 5 |
| 33 at ground |
and
| HCU (4310EG-A) Connector Contacts | EIU (AB) Connector Contacts |
|---|---|
| 5 | 15G |
1 Connect all connectors disconnected.
2 Do the test given in Para. 3.
(8) If no problems with the aircraft wiring are found or the fault continues:
(a) Replace HCU-T/R, ENG1 [4310EG1] or HCU-T/R, ENG2 [4310EG2] AMM 78-31-01-000-801 and AMM 78-31-01-400-801.
(b) Do the test given in Para. 3.
(9) If the fault continues:
(a) Replace
(b) Do the test given in Para. 3.
Subtask 73-25-00-860-081-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.