N2 Sensor Electrical Failure on Channel B

TASK 77-11-00-810-812-A
N2 Sensor Electrical Failure on Channel B

1. Possible Causes

TRANSDUCER-N2 [4065KS]
W03 HARNESS [4087KS]
[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 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 77-11-23-000-801	Remove the N2 Speed Transducer
AMM 77-11-23-400-801	Install the N2 Speed Transducer
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 Harnesses
N2 Speed Transducer Wiring Harnesses
N2 Speed Transducer Wiring Schematic

3. Fault Confirmation
Subtask 77-11-00-710-062-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 MCDU screen, make sure that the fault is not displayed on ground scan report.

NOTE: The Electronic Engine Control (EEC) has detected the N2 speed transducer circuit is out of range or rate in channel B. The N2 speed transducer is mounted on angle gearbox, located at the 5 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 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.
(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 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 77-11-00-810-064-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 W03 (4087KS) harness, connector P4 (4000KS-P4) - EEC (4000KS) and connector P64 (4065KS-P64) - N2 speed transducer (4065KS), for problems which are possible between the EEC (4000KS) and the N2 speed transducer (4065KS).
(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 W03 HARNESS(4087KS) AMM 73-21-63-000-802 and AMM 73-21-63-400-802.
2 Do the test given in Para. 3.
(3) If no problems are found with the harness, use a PLIERS - JAWED, SOFT to disconnect electrical connector P4 (4000KS-P4) from the EEC (4000KS) and connector P64 (4065KS-P64) from the N2 speed transducer (4065KS).
(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 the electrical connector P4 (4000KS-P4) to the EEC (4000KS) and connector P64 (4065KS-P64) to the N2 speed transducer (4065KS).
(d) Do the test given in Para. 3.
(4) If the fault continues:
(a) Replace TRANSDUCER-N2 [4065KS] AMM 77-11-23-000-801 and AMM 77-11-23-400-801.
(b) Do the test given in Para. 3.
(5) If the fault continues:
(a) Disconnect the electrical connector P4 (4000KS-P4) from the EEC (4000KS) and connector P64 (4065KS-P64) from the N2 speed transducer (4065KS). Use a MULTIMETER - STANDARD to test the N2 speed transducer (4065KS) circuits 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: N2 Speed Probe Channel B Connector Contacts

W03 (4087KS) Harness P4 (4000KS-P4) EEC (4000KS) Connector Contacts	W03 (4087KS) Harness P64 (4065KS-P64) N2 Speed Transducer (4065KS) Connector Contacts
Y	4
t	5

(b) If a problem is found with the harness or connectors:
1 Replace W03 HARNESS [4087KS] AMM 73-21-63-000-802 and AMM 73-21-63-400-802.
2 Do the test given in Para. 3.
(6) If the fault continues:
(a) Replace [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 77-11-00-860-054-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 04:40:57 UTC