LOP Switch in High Pressure when Engine is not Running

TASK 79-33-00-810-842-A
LOP Switch in High Pressure when Engine is not Running

1. Possible Causes

SW-LOW OIL PRESS [4080KS]
LOP Switch Harness (4155KS)
EIU-1 [1KS1]
EIU-2 [1KS2]
[4000KS]

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

B. Referenced Information

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 73-25-34-000-802	Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-400-802	Installation of the Engine Interface Unit (EIU)
AMM 73-25-34-860-806	Engine Interface Unit (EIU) DISCRETE INPUTS Menu Data Status
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 79-33-25-000-801	Removal of the Low Oil Pressure (LOP) Switch
AMM 79-33-25-400-801	Installation of the Low Oil Pressure (LOP) Switch
Main Oil Presure Sensor Wiring Harness

3. Fault Confirmation
Subtask 79-33-00-710-112-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.

NOTE: The Electronic Engine Control (EEC) has detected the circuit for the Low Oil Pressure (LOP) switch is out of range or rate in channel A or channel B. The LOP signal is sent to the EEC from the Engine Indicating Unit (EIU). The LOP switch is mounted on the oil control manifold, located at the 9 o'clock position. The EEC is located on the fan case at the 2 o'clock position.

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).

(3) 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).
(a) If no problems are found, return the engine to service. Monitor the engine for reoccurring maintenance message.
(4) If the maintenance message comes back (hard fault), go to the Para. Fault Isolation.

4. 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 79-33-00-810-095-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 LOP pressure switch harness (4155KS) and connector P70 (4080KS-P70) - LOP switch (4080KS), for problems which are possible between the EEC (4000KS) and the LOP switch (4080KS).
(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 LOP switch harness (4155KS) AMM 71-51-40-000-801 and AMM 71-51-40-400-801.
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 electrical 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 connector P70 (4080KS-P70) to the LOP switch (4080KS).
(d) 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 no problems are found from the LOP switch (4080KS) or the fault continues:
(a) Disconnect electrical connector P70 (4080KS-P70) from the LOP switch (4080KS). Use a MULTIMETER - STANDARD to test the LOP switch (4080KS) circuits in the LOP switch harness (4155KS). 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: LOP Switch Connector Contacts

LOP Switch Harness P70 (4080KS-P70) LOP Switch(4080KS) Connector Contacts	404VC-A Connector Contacts
3	8
2	19

(b) If a problem is found with the harnesses or connectors:
1 Replace LOP Switch Harness (4155KS) AMM 71-51-40-000-801 and AMM 71-51-40-400-801.
2 Do the test given in Para. 3.
(6) If no problems are found with the harnesses or the fault continues, check the aircraft wiring:
(a) Reconnect all connectors.
(b) Check the status of LOP in Engine Interface Unit (EIU) AMM 73-25-34-860-806.
1 Check the status is at 1.
2 If the status is not correct, repair or replace aircraft wiring AWM 732560.
3 If the status is correct, replace EIU-1 [1KS1] or 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 no problems are found and the fault continues:
(a) Replace the [4000KS] AMM 73-21-01-000-801 and AMM 73-21-01-400-801.
(b) Do the test given in Para. 3.

5. Close-up
Subtask 79-33-00-860-069-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.

[Rev.8 from Aug 2018] 2026.04.04 04:38:31 UTC