PHMU CAN Fault

TASK 77-31-00-810-802-A
PHMU CAN Fault

1. Possible Causes

PROGNOSTICS AND HEALTH MANAGEMENT UNIT [4609KS]
HARNESS-FAN, WF01 [4217KS]
HARNESS-FAN, WF02 [4218KS]
[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 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002	De-energize the Aircraft Electrical Circuits Supplied from the External Power
AMM 70-70-00-910-803	SPOP 6 - Cleaning of the Contact Points and Wiring Harnesses
AMM 71-13-00-010-802	Opening of the Fan Cowl Doors
AMM 71-13-00-410-802	Closing of the Fan Cowl Doors
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 73-21-61-000-802	Removal of the Electronic Engine Control (EEC) Wiring Harness (WF01)
AMM 73-21-61-400-802	Installation of the Electronic Engine Control (EEC) Wiring Harness (WF01)
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)
AMM 77-31-01-000-801	Removal of the Prognostics and Health Management Unit (PHMU)
AMM 77-31-01-400-801	Installation of the Prognostics and Health Management Unit (PHMU)
EEC and PHMU Wiring Harnesses
WF01 and WF02 Interconnect Wiring Harnesses
PHMU Wiring Schematic

3. Fault Confirmation
Subtask 77-31-00-710-051-A ** ON A/C NOT FOR ALL

A. Energize the FADEC of the engine that has a 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 switch (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 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 a fault in the Controller Area Network (CAN) bus communication circuits for the Prognostic and Health Management Unit (PHMU). The PHMU is located at the 2 o'clock position of the fan case adjacent to the EEC.

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).

(4) 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.
(5) If the maintenance message comes back (hard fault) in channel A and channel B, 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 77-31-00-810-051-A ** ON A/C NOT FOR ALL

A. If there is confirmation of the fault:
(1) Open the fan cowl doors AMM 71-13-00-010-802.
(2) Examine the WF01 (4217KS) and WF02 (4218KS) harnesses, connectors P1 (4000KS-P1) and P2 (4000KS-P2) - EEC (4000KS), interconnect P103 (4105VC-A)/ J103 (4105VC) and connector P9 (4609KS-P9) - PHMU (4609KS), for problems which are possible between the EEC (4000KS) and the PHMU (4609KS).
(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 harnesses or connectors:
1 Replace WF01 HARNESS-FAN(4217KS) AMM 73-21-61-000-802 and AMM 73-21-61-400-802, or
2 Replace WF02 HARNESS-FAN(4218KS) AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
3 Do the test given in Para. 3.
(3) If no problems are found with the harnesses or the fault continue, use a PLIERS - JAWED, SOFT to disconnect the electrical connectors P1 (4000KS-P1) and P2 (4000KS-P2) from the EEC (4000KS), interconnect P103 (4105VC-A)/J103 (4105VC) and connector P9 (4609KS-P9) from the PHMU (4609KS).
(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 connectors P1 (4000KS-P1) and P2 (4000KS-P2) to the EEC (4000KS), interconnect P103 (4105VC-A)/J103 (4105VC) and connector P9 (4609KS-P9) to the PHMU (4609KS).
(d) Do the test given in Para. 3.
(4) If the fault continues:
(a) Replace PROGNOSTICS AND HEALTH MANAGEMENT UNIT [4609KS] AMM 77-31-01-000-801 and AMM 77-31-01-400-801.
(b) Do the test given in Para. 3.
(5) If the fault continues:
(a) Disconnect the electrical connectors P1 (4000KS-P1) and P2 (4000KS-P2) from the EEC (4000KS), interconnect P103 (4105VC-A)/J103 (4105VC) and connector P9 (4609KS-P9) from the PHMU (4609KS). Use a MULTIMETER - STANDARD to test the PHMU (4609KS) CAN Bus communication 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: EEC to PHMU Channel A CAN Bus Communication Connector Contacts

WF02 (4218KS) Harness P1(4000KS-P1) EEC (4000KS) Connector Contacts	WF02 (4218KS) Harness P9(4609KS-P9) PHMU (4609KS) Connector Contacts
Y	H
u	G

Table 2: EEC to PHMU Channel B CAN Bus Communication Connector Contacts

WF01 (4217KS) Harness P2 (4000KS-P2) EEC (4000KS) Connector Contacts	WF01 (4217KS) Harness P103 (4105VC-A) Connector Contacts	WF02 (4218KS) Harness J103 (4105VC) Connector Contacts	WF02 (4218KS) Harness P9 (4609KS-P9) PHMU (4609KS) Connector Contacts
Y	4	4	Y
u	5	5	X

(b) If a problem is found with the harnesses or connectors:
1 Replace HARNESS-FAN, WF01 [4217KS] AMM 73-21-61-000-802 and AMM 73-21-61-400-802, or
2 Replace HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802.
3 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 77-31-00-860-051-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.
(b) De-energize the aircraft electrical circuits AMM 24-41-00-862-002.

[Rev.8 from Aug 2018] 2026.04.04 04:40:52 UTC