DOC AIRBUS | TSM A320FDisagreement between Main Oil Pressure Signal and LOP Switch
TASK 79-21-00-810-829-A
Disagreement between Main Oil Pressure Signal and LOP Switch
1. Possible Causes
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Fault Confirmation
Subtask 79-21-00-710-076-A ** ON A/C NOT FOR ALL
Subtask 79-21-00-860-069-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:38:36 UTC
Disagreement between Main Oil Pressure Signal and LOP Switch
1. Possible Causes
- SENSOR-PRESSURE, MAIN OIL [4071KS]
- SW-LOW OIL PRESS [4080KS]
- W04 HARNESS [4088KS]
- W03 HARNESS [4087KS]
- WC10 HARNESS-CORE [4011KS]
- HARNESS-IDG, ENG PUMP AND LOW OIL PRESS SW [4155KS]
[4000KS] - EIU-1 [1KS1]
- EIU-2 [1KS2]
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 70-70-00-910-803 | SPOP 6 - Cleaning of the Contact Points and Wiring Harnesses |
| AMM 71-00-00-860-814 | Shutdown of the Engine |
| AMM 71-00-00-860-822 | Start the Engine (Normal Manual Start) |
| AMM 71-00-00-860-823 | Start the Engine (Normal Automatic Start) |
| AMM 71-51-40-000-801 | Removal of the IDG-EDP-MON Harness |
| AMM 71-51-40-400-801 | Installation of the IDG-EDP-MON Harness |
| 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 73-21-63-000-802 | Removal of the Electronic Engine Control (EEC) Wiring Harness (W03) |
| AMM 73-21-63-400-802 | Installation of the Electronic Engine Control (EEC) Wiring Harness (W03) |
| AMM 73-21-64-000-802 | Removal of the Electronic Engine Control (EEC) Wiring Harness (W04) |
| AMM 73-21-64-400-802 | Installation of the Electronic Engine Control (EEC) Wiring Harness (W04) |
| AMM 73-21-69-000-802 | Removal of the EEC Wiring Harness (WC10) |
| AMM 73-21-69-400-802 | Installation of the EEC Wiring Harness (WC10) |
| 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) |
| AWM 732560 | |
| 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 |
| AMM 79-33-21-000-801 | Removal of the Main Oil Pressure (MOP) Sensor |
| AMM 79-33-21-400-801 | Installation of the Main Oil Pressure (MOP) Sensor |
| AMM 79-33-25-000-801 | Removal of the Low Oil Pressure (LOP) Switch |
| AMM 79-33-25-400-801 | Installation of the Low Oil Pressure (LOP) Switch |
W03/W04 Interconnect Wiring HarnessSubtask 79-21-00-710-076-A ** ON A/C NOT FOR ALL
A. Do an engine run to idle to confirm repair of this fault AMM 71-00-00-860-822 or AMM 71-00-00-860-823.
(1) Shutdown the engine AMM 71-00-00-860-814.
(2) On Multipurpose Control and Display Unit (MCDU) screen, check if the fault is displayed on ground scanning report.
(a) Do a check for maintenance messages regarding faults related to the main oil pressure sensor (4071KS) and LOP switch (4080KS).
(b) Troubleshoot any maintenance messages found.
(4) If no maintenance messages are found, examine the harnesses and electrical connectors as described in the component and harness intermittent fault isolation procedure (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.
(5) If the maintenance message comes back (hard fault), go to the Para. Fault Isolation.
4. Fault Isolation(1) Shutdown the engine AMM 71-00-00-860-814.
(2) On Multipurpose Control and Display Unit (MCDU) screen, check if the fault is displayed on ground scanning report.
NOTE: The Electronic Engine Control (EEC) has detected the oil pressure feedback signals from the Main Oil Pressure (MOP) sensor circuit and the Low Oil Pressure (LOP) switch circuit do not agree. The main oil pressure sensor provides feedback to the EEC and the LOP switch provides feedback to the Electronic Interface Unit (EIU) located in the aircraft electronic deck. The EIU relays the oil pressure feedback from the LOP switch to the EEC. The main oil pressure sensor and the LOP switch are mounted on the oil control manifold located at the 9 o'clock position.
(3) If the maintenance message does not come back, do the steps that follow: - 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) Do a check for maintenance messages regarding faults related to the main oil pressure sensor (4071KS) and LOP switch (4080KS).
(b) Troubleshoot any maintenance messages found.
(4) If no maintenance messages are found, examine the harnesses and electrical connectors as described in the component and harness intermittent fault isolation procedure (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.
(5) 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 AND ENGINE OIL 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 79-21-00-810-080-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) Do a check for maintenance messages regarding faults related to the main oil pressure sensor (4071KS) and the LOP switch (4080KS).
(a) Troubleshoot any maintenance messages found.
(b) Do the test given in Para. 3.
(3) If no maintenance messages are found or the fault continues:
(a) Replace SENSOR-PRESSURE, MAIN OIL [4071KS] AMM 79-33-21-000-801 and AMM 79-33-21-400-801.
(b) Do the test given in Para. 3.
(4) If the fault continues:
(a) Replace SW-LOW OIL PRESS [4080KS] AMM 79-33-25-000-801 and AMM 79-33-25-400-801.
(b) Do the test given in Para. 3.
(5) If the fault continues:
(a) Examine the W04 (4088KS), W03 (4087KS) and WC10 (4011KS) harnesses and connectors P5 (4000KS-P5) and P6 (4000KS-P6) - EEC (4000KS), interconnect J106 (4100VC)/P106 (4100VC-A), interconnect J110 (4110VC)/P110 (4110VC-A) and connector P38 (4071KS-P38) - Main oil pressure sensor (4071KS) and connector P70 (4080KS-P70) - LOP switch (4080KS), for problems which are possible between the EEC (4000KS), the main oil pressure sensor (4071KS) and the LOP switch (4080KS).
(b) Inspect for harness damage.
(c) Inspect for loose or damaged connectors.
1 Replace W04 HARNESS [4088KS] AMM 73-21-64-000-802 and AMM 73-21-64-400-802, or
2 Replace W03 HARNESS [4087KS] AMM 73-21-63-000-802 and AMM 73-21-63-400-802, or
3 Replace WC10 HARNESS-CORE [4011KS] AMM 73-21-69-000-802 and AMM 73-21-69-400-802.
4 Do the test given in Para. 3.
(6) If no problems are found with the harnesses or the fault continues, use a PLIERS - JAWED, SOFT to disconnect electrical connectors P5 (4000KS-P5) and P6 (4000KS-P6) from the EEC (4000KS), interconnect J106 (4100VC)/P106 (4100VC-A), interconnect J110 (4110VC)/P110 (4110VC-A) and connector P38 (4071KS-P38) from the main oil pressure sensor (4071KS) and connector P70 (4080KS-P70) from the LOP switch (4080KS).
(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 the connector face AMM 70-70-00-910-803.
(c) Reconnect electrical connectors P5 (4000KS-P5) and P6 (4000KS-P6) to the EEC (4000KS), interconnect J106 (4100VC)/P106 (4100VC-A), interconnect J110 (4110VC)/P110 (4110VC-A) and connector P38 (4071KS-P38) to the main oil pressure sensor (4071KS) and connector P70 (4080KS-P70) to the LOP switch (4080KS).
(d) Do the test given in Para. 3.
(7) If the fault continues:
(a) Disconnect electrical connectors P5 (4000KS-P5) and P6 (4000KS-P6) from the EEC (4000KS), interconnect J106 (4100VC)/P106 (4100VC-A), interconnect J110 (4110VC)/P110 (4110VC-A) and connector P38 (4071KS-P38) from the main oil pressure sensor (4071KS). Use a MULTIMETER - STANDARD to test the main oil pressure sensor (4071KS) circuits in the harnesses. Refer to Table 1 and Table 2. Look for:
1 Wire-to-wire shorts
2 Shorts to ground
3 Continuity (less than 5 ohms resistance).
Table 2: Main Oil Pressure Sensor Channel B Connector Contacts
(b) If a problem is found with the harnesses or connectors:
1 Replace W04 HARNESS [4088KS] AMM 73-21-64-000-802 and AMM 73-21-64-400-802, or
2 Replace W03 HARNESS [4087KS] AMM 73-21-63-000-802 and AMM 73-21-63-400-802, or
3 Replace WC10 HARNESS-CORE [4011KS] AMM 73-21-69-000-802 and AMM 73-21-69-400-802.
4 Do the test given in Para. 3.
(8) If the fault continues:
(a) Disconnect the electrical connector P70 (4080KS-P70) from the LOP switch (4080KS) and connector 404VC-A from the pylon junction box. Used a MULTIMETER - STANDARD to test the LOP switch (4080KS) circuit in the harness. Refer to Table 3. Look for:
(b) Wire-to-wire shorts
(c) Shorts to ground
(d) Continuity (less than 5 ohms resistance).
(e) If a problem is found with the harness or connectors:
1 Replace HARNESS-IDG, ENG PUMP AND LOW OIL PRESS SW [4155KS] AMM 71-51-40-000-801 and AMM 71-51-40-400-801.
2 Do the test given in Para. 3.
(9) If no problems are found with the harness or the fault continues:
(a) Do a check of the aircraft wiring AWM 732560. Look for:
1 Wire-to-wire shorts
2 Shorts to ground
3 Continuity (less than 5 ohms resistance).
4 Do the test given in Para. 3.
(10) If the fault continues:
(a) Replace
(b) Do the test given in Para. 3.
(11) If the fault continues:
(a) Replace EIU-1 [1KS1] or EIU-2 [1KS2] AMM 73-25-34-000-802 and AMM 73-25-34-400-802.
(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) Do a check for maintenance messages regarding faults related to the main oil pressure sensor (4071KS) and the LOP switch (4080KS).
(a) Troubleshoot any maintenance messages found.
(b) Do the test given in Para. 3.
(3) If no maintenance messages are found or the fault continues:
(a) Replace SENSOR-PRESSURE, MAIN OIL [4071KS] AMM 79-33-21-000-801 and AMM 79-33-21-400-801.
(b) Do the test given in Para. 3.
(4) If the fault continues:
(a) Replace SW-LOW OIL PRESS [4080KS] AMM 79-33-25-000-801 and AMM 79-33-25-400-801.
(b) Do the test given in Para. 3.
(5) If the fault continues:
(a) Examine the W04 (4088KS), W03 (4087KS) and WC10 (4011KS) harnesses and connectors P5 (4000KS-P5) and P6 (4000KS-P6) - EEC (4000KS), interconnect J106 (4100VC)/P106 (4100VC-A), interconnect J110 (4110VC)/P110 (4110VC-A) and connector P38 (4071KS-P38) - Main oil pressure sensor (4071KS) and connector P70 (4080KS-P70) - LOP switch (4080KS), for problems which are possible between the EEC (4000KS), the main oil pressure sensor (4071KS) and the LOP switch (4080KS).
(b) Inspect for harness damage.
(c) Inspect for loose or damaged connectors.
NOTE: Loose connectors must be disconnected and examined for further wear or damage.
(d) If a problem is found with the harnesses or connectors: 1 Replace W04 HARNESS [4088KS] AMM 73-21-64-000-802 and AMM 73-21-64-400-802, or
2 Replace W03 HARNESS [4087KS] AMM 73-21-63-000-802 and AMM 73-21-63-400-802, or
3 Replace WC10 HARNESS-CORE [4011KS] AMM 73-21-69-000-802 and AMM 73-21-69-400-802.
4 Do the test given in Para. 3.
(6) If no problems are found with the harnesses or the fault continues, use a PLIERS - JAWED, SOFT to disconnect electrical connectors P5 (4000KS-P5) and P6 (4000KS-P6) from the EEC (4000KS), interconnect J106 (4100VC)/P106 (4100VC-A), interconnect J110 (4110VC)/P110 (4110VC-A) and connector P38 (4071KS-P38) from the main oil pressure sensor (4071KS) and connector P70 (4080KS-P70) from the LOP switch (4080KS).
(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 the connector face AMM 70-70-00-910-803.
(c) Reconnect electrical connectors P5 (4000KS-P5) and P6 (4000KS-P6) to the EEC (4000KS), interconnect J106 (4100VC)/P106 (4100VC-A), interconnect J110 (4110VC)/P110 (4110VC-A) and connector P38 (4071KS-P38) to the main oil pressure sensor (4071KS) and connector P70 (4080KS-P70) to the LOP switch (4080KS).
(d) Do the test given in Para. 3.
(7) If the fault continues:
(a) Disconnect electrical connectors P5 (4000KS-P5) and P6 (4000KS-P6) from the EEC (4000KS), interconnect J106 (4100VC)/P106 (4100VC-A), interconnect J110 (4110VC)/P110 (4110VC-A) and connector P38 (4071KS-P38) from the main oil pressure sensor (4071KS). Use a MULTIMETER - STANDARD to test the main oil pressure sensor (4071KS) circuits in the harnesses. Refer to Table 1 and Table 2. 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: Main Oil Pressure Sensor Channel A Connector Contacts | W04 (4088KS) Harness P5 (4000KS-P5) EEC (4000KS) Connector Contacts | W04(4088KS) Harness J106 (4100VC) Connector Contacts | W03(4087KS) Harness P106 (4100VC-A) Connector Contacts | W03(4087KS) Harness J110 (4110VC) Connector Contacts | WC10(4011KS) Harness P110 (4110VC-A) Connector Contacts | WC10(4011KS) Harness P38 (4071KS-P38) MOP Sensor (4071KS) Connector Contacts |
|---|---|---|---|---|---|
| CC | 14 | 14 | 33 | 33 | 12 |
| R | 15 | 15 | 34 | 34 | 4 |
| p | 30 | 30 | 35 | 35 | 3 |
| S | 31 | 31 | 36 | 36 | 11 |
Table 2: Main Oil Pressure Sensor Channel B Connector Contacts
| W03 (4087KS) Harness P6 EEC (4000KS) Connector Contacts | W03 (4087KS) Harness J110 (4110VC) Connector Contacts | WC10 (4011KS) Harness P110 (4110VC-A) Connector Contacts | WC10 (4011KS) Harness P38 Main Oil Pressure Sensor (4071KS) Connector Contacts |
|---|---|---|---|
| CC | 25 | 25 | 9 |
| R | 26 | 26 | 8 |
| p | 27 | 27 | 7 |
| S | 28 | 28 | 6 |
1 Replace W04 HARNESS [4088KS] AMM 73-21-64-000-802 and AMM 73-21-64-400-802, or
2 Replace W03 HARNESS [4087KS] AMM 73-21-63-000-802 and AMM 73-21-63-400-802, or
3 Replace WC10 HARNESS-CORE [4011KS] AMM 73-21-69-000-802 and AMM 73-21-69-400-802.
4 Do the test given in Para. 3.
(8) If the fault continues:
(a) Disconnect the electrical connector P70 (4080KS-P70) from the LOP switch (4080KS) and connector 404VC-A from the pylon junction box. Used a MULTIMETER - STANDARD to test the LOP switch (4080KS) circuit in the harness. Refer to Table 3. Look for:
(b) Wire-to-wire shorts
(c) Shorts to ground
(d) 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: LOP Switch Connector Contacts | IDG ENG PUMP AND LOP SW (4155KS) Harness P70 (4080KS-P70) LOP switch (4080KS) Connector Contacts | 404VC-A Connector Contacts |
|---|---|
| 1 | 8 |
| 2 | 19 |
1 Replace HARNESS-IDG, ENG PUMP AND LOW OIL PRESS SW [4155KS] AMM 71-51-40-000-801 and AMM 71-51-40-400-801.
2 Do the test given in Para. 3.
(9) If no problems are found with the harness or the fault continues:
(a) Do a check of the aircraft wiring AWM 732560. Look for:
1 Wire-to-wire shorts
2 Shorts to ground
3 Continuity (less than 5 ohms resistance).
4 Do the test given in Para. 3.
(10) If the fault continues:
(a) Replace
(b) Do the test given in Para. 3.
(11) If the fault continues:
(a) Replace EIU-1 [1KS1] or EIU-2 [1KS2] AMM 73-25-34-000-802 and AMM 73-25-34-400-802.
(b) Do the test given in Para. 3.
Subtask 79-21-00-860-069-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.