Loss of the EGT Thermocouples on Engine 2

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1. Possible Causes
NOTE: This task is to troubleshoot the Clear Language Message (CLM) EGT SENS/HC/EEC2. The fault acronyms
listed in the fault confirmation section below will help you to focus on the correct cause of this CLM.
· harness from the EEC connector (4000KS-J4) to the junction BOX-EGT (4012KS5)
· core EGT harness
· EGT harness between the junction BOX-EGT (4012KS5) and the thermocouple-EGT 1 to 4 (4012KS1,
4012KS2, 4012KS3, 4012KS4)
· EGT harness
· EGT thermocouples
· JUNCTION BOX-EGT ( 4012KS5 )
· EEC ( 4000KS )
· harness from the EEC connector (4000KS-J10) to the junction BOX-EGT (4012KS5)
· EGT harness between the junction BOX-EGT (4012KS5) and the thermocouple-EGT 1 to 4 (4012KS1,
4012KS2, 4012KS3, 4012KS4)
· harness between the junction BOX-EGT (4012KS5) and the thermocouple-EGT 1 to 4 (4012KS1, 4012KS2,
4012KS3, 4012KS4)
2 Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
REFERENCE QTY DESIGNATION
No specific 1 HOT AIR SOURCE
No specific 1 NITROGEN COMPRESSED SOURCE - GROUND
B. Referenced Information
REFERENCE DESIGNATION
Ref. AMM 24-41-00-861-002 Energize the Aircraft Electrical Circuits from the External Power
Ref. AMM 24-41-00-862-002 De-energize the Aircraft Electrical Circuits Supplied from the External
Power
Ref. AMM 31-60-00-860-002 EIS Stop Procedure
Ref. AMM 70-23-15-912-010 Connection of Electrical Connectors
Ref. AMM 71-13-00-410-010 Closing of the Fan Cowls 437AL(447AL),438AR(448AR)
Ref. AMM 71-50-00-210-010 Wire Harness Visual Inspection - All Power Plant Electrical Cables
Ref. AMM 73-22-00-710-040 Operational Test of the FADEC SYSTEM on the Ground
Ref. AMM 73-22-34-000-010 Removal of the Electronic Engine Control (EEC)
Ref. AMM 73-22-34-400-010 Installation of the Electronic Engine Control (EEC)
Ref. ASM 73-25-15
Ref. AMM 77-21-15-000-010 Removal of the Exhaust Gas Temperature (EGT) Thermocouple
Ref. AMM 77-21-15-400-010 Installation of the Exhaust Gas Temperature (EGT) Thermocouple
Ref. AMM 77-21-43-000-010 Removal of the EGT Harness and Junction Box
Ref. AMM 77-21-43-400-010 Installation of the EGT Harness and Junction Box
Ref. AMM 77-21-43-700-010 Functional Test of the EGT Harness, Junction Box and Thermocouples
Ref. AMM 78-30-00-440-012 Re-activation of the Thrust Reverser Hydraulic Control Unit (HCU) after
Ground Maintenance
Ref. AMM 78-32-00-410-010 Closing of the Thrust Reverser Halves
70-00-00-03-13 STANDARD PRACTICES - ENGINE - GENERAL - TASK SUPPORTING
DATA
EGT Indication Circuit SHEET 1
Direction of Nitrogen or Hot Air for Dry Out of Junction box SHEET 1
Figure 77(IAE)-20-00-991-00100-A / SHEET 1/1 - EGT Indication Circuit not printed, as per printing
preferences
Figure 77(IAE)-20-00-991-00300-A / SHEET 1/1 - Direction of Nitrogen or Hot Air for Dry Out of
Junction box not printed, as per printing preferences
3. Fault Confirmation
Subtask 77-20-00-860-054-A
A. Job Set-up
(1) Energize the aircraft electrical circuits
Ref. AMM 24-41-00-861-002 .
(2) On the ENG section of the maintenance panel 50VU, select FADEC GND PWR 2 pushbutton switch
to the ON position.
Subtask 77-20-00-710-054-A
B. Identify the Test for Fault Confirmation
NOTE: Troubleshooting can start immediately without doing the fault confirmation if this CLM was shown
in multiple flight or ground legs.
(1) Do the CFDS message decoding and read the scheduled maintenance report to identify the fault
acronym related to the CLM (Ref. TSM 70-00-00-03) .
(2) If the readout gives fault acronym T5L or T5XCF in FADEC 2A or FADEC 2B, do the steps in Para
3.C. for fault confirmation (test of the FADEC system to confirm the fault).
(a) If the test gives the fault acronym T5L or there are two or more occurrences in fault history,
continue with fault isolation Para 4.A.
(b) If the test gives the fault acronym T5XCF or there are two or more occurrences in fault history,
continue with fault isolation Para 4.B.
(c) If the test does not give the fault acronym T5L or T5XCF and there is no history of faults, send
the engine back to service.
Subtask 77-20-00-710-117-A
C. Test for Fault Acronym T5L or T5XCF
(1) Do the procedure given in Ref. AMM 73-22-00-710-040 .
(2) Read the LAST LEG REPORT and the scheduled maintenance report of the FADEC 2A and FADEC
2B menu on the MCDU (Ref. TSM 70-00-00-03) .
(a) Make a record of the fault message.
(b) Make a record of the channel FADEC 2A or FADEC 2B which found the fault.
(c) Do the CFDS message decoding and read the flight data and ground data to identify the fault
acronym.
4. Fault Isolation
(Ref. Fig. EGT Indication Circuit SHEET 1)
Subtask 77-20-00-810-052-A
A. Fault Isolation for Fault Acronym T5L
· The EGT thermocouple signal is out of range. This is caused by an open, short to ground or a wire to
wire short in this circuit.
NOTE: After each step that is done during this procedure, you can do the steps in Para 3. to make sure
the fault is corrected.
NOTE: Disconnection and connection of the electrical connectors can correct this fault.
(1) If the fault was found in channel A, do the steps that follow:
(a) Visually examine the harness from the EEC connector (4000KS-J4) to the junction BOX-EGT
(4012KS5) Ref. AMM 71-50-00-210-010 and Ref. ASM 73-25-15.
1 Look for harness damage.
2 Look for loose or damaged connectors.
3 Look for loose or damaged backshells.
NOTE: Loose backshells must be disassembled and examined for internal wiring chafing.
4 If a problem is found with the harness, repair as necessary or replace the core EGT
harness and Ref. ASM 73-25-15.
(b) Visually examine the EGT harness between the junction BOX-EGT (4012KS5)
and the thermocouple-EGT 1 to 4 (4012KS1, 4012KS2, 4012KS3, 4012KS4) Ref.
AMM 71-50-00-210-010 and Ref. ASM 73-25-15.
1 Look for harness damage.
2 If a problem is found with the harness, repair as necessary or replace the EGT harness
Ref. AMM 77-21-43-000-010 and Ref. AMM 77-21-43-400-010 and Ref. ASM 73-25-15.
3 If moisture is found on the EGT harness or junction box, you can apply NITROGEN
COMPRESSED SOURCE - GROUND or HOT AIR SOURCE, or the harness can be
restored by the bake procedure in the vendor CMM.
(Ref. Fig. Direction of Nitrogen or Hot Air for Dry Out of Junction box SHEET 1)
(c) Do the functional test of the EGT harness, junction box and thermocouples Ref.
AMM 77-21-43-700-010 .
1 Repair or replace if necessary the EGT harness Ref. AMM 77-21-43-000-010 and Ref.
AMM 77-21-43-400-010 .
2 Replace if necessary the EGT thermocouples Ref. AMM 77-21-15-000-010 and Ref.
AMM 77-21-15-400-010 .
3 Replace if necessary the JUNCTION BOX-EGT ( 4012KS5 ) Ref. AMM 77-21-43-000-010
and Ref. AMM 77-21-43-400-010 .
(d) If no problems were found, disconnect electrical connector (4000KS-J4) from the
EEC ( 4000KS ) . Examine the male and female parts of the connection Ref.
AMM 71-50-00-210-010 .
1 Examine pins and sockets (contacts) for alignment and damage.
2 Look for contacts pushed rearward into the connector face.
3 Look for ovalized sockets in the connector.
NOTE: This can be done by inserting a harness connector pin into each socket. You must
feel friction when you insert and remove the pin.
4 Repair as necessary.
(e) Do this electrical check of the harness in channel A. Look for:
1 Wire to wire shorts and shorts to ground.
· Wire to wire short check: measure resistance between wires. If resistance is below
100000 (100K) ohms, then the wires are shorted and must be repaired.
· Wire to ground short check: measure resistance between wire and engine metal or
ground. If resistance is below 100000 (100K) ohms, then the wire is shorted to ground and
must be repaired.
2 Continuity.
· Continuity check: measure resistance between ends of same wire. If resistance is more
than 10 ohms, then the wire must be repaired.
NOTE: An incorrectly wired harness can cause this problem. When you test these circuits,
make sure the contacts are installed in the correct positions in each connector as
specified in the wiring diagram.
EGT Thermocouple Circuit Channel A Harness
JUNCTION BOX-EGT (4012KS5) EEC (4000KS)
(4012KS5-A) (4000KS-J4)
Contacts Contacts
Chromel lug (smaller) Y
Alumel lug (larger) B
3 If a problem is found with the harness, repair as necessary or replace the core EGT
harness and Ref. ASM 73-25-15.
(f) Install all removed connectors Ref. AMM 70-23-15-912-010 .
(g) Do the test for this fault, listed in Para 3. for fault confirmation.
1 If the test does not give the fault acronym T5L, send the engine back to service.
2 If the test gives the fault acronym T5L, remove and replace the EEC ( 4000KS ) Ref.
AMM 73-22-34-000-010 and Ref. AMM 73-22-34-400-010 .
(2) If the fault was found in channel B, do the steps that follow:
(a) Visually examine the harness from the EEC connector (4000KS-J10) to the junction BOX-EGT
(4012KS5) Ref. AMM 71-50-00-210-010 and Ref. ASM 73-25-15.
1 Look for harness damage.
2 Look for loose or damaged connectors.
3 Look for loose or damaged backshells.
NOTE: Loose backshells must be disassembled and examined for internal wiring chafing.
4 If a problem is found with the harness, repair as necessary or replace the core EGT
harness and Ref. ASM 73-25-15.
(b) Visually examine the EGT harness between the junction BOX-EGT (4012KS5)
and the thermocouple-EGT 1 to 4 (4012KS1, 4012KS2, 4012KS3, 4012KS4) Ref.
AMM 71-50-00-210-010 and Ref. ASM 73-25-15.
1 Look for harness damage.
2 If a problem is found with the harness, repair as necessary or replace the EGT harness
Ref. AMM 77-21-43-000-010 and Ref. AMM 77-21-43-400-010 and Ref. ASM 73-25-15.
3 If moisture is found on the EGT harness or junction box, you can apply NITROGEN
COMPRESSED SOURCE - GROUND or HOT AIR SOURCE, or the harness can be
restored by the bake procedure in the vendor CMM.
(Ref. Fig. Direction of Nitrogen or Hot Air for Dry Out of Junction box SHEET 1)
(c) Do the functional test of the EGT harness, junction box and thermocouples Ref.
AMM 77-21-43-700-010 .
1 Repair or replace if necessary the EGT harness Ref. AMM 77-21-43-000-010 and Ref.
AMM 77-21-43-400-010 .
2 Replace if necessary the EGT thermocouples Ref. AMM 77-21-15-000-010 and Ref.
AMM 77-21-15-400-010 .
3 Replace if necessary the JUNCTION BOX-EGT ( 4012KS5 ) Ref. AMM 77-21-43-000-010
and Ref. AMM 77-21-43-400-010 .
(d) If no problems were found, disconnect electrical connector (4000KS-J10) from
the EEC ( 4000KS ) . Examine the male and female parts of the connection Ref.
AMM 71-50-00-210-010 :
1 Examine pins and sockets (contacts) for alignment and damage.
2 Look for contacts pushed rearward into the connector face.
3 Look for ovalized sockets in the connector.
NOTE: This can be done by inserting a harness connector pin into each socket. You must
feel friction when you insert and remove the pin.
4 Repair as necessary.
(e) Do this electrical check of the harness in channel B. Look for:
1 Wire to wire shorts and shorts to ground.
· Wire to wire short check: measure resistance between wires. If resistance is below
100000 (100K) ohms, then the wires are shorted and must be repaired.
· Wire to ground short check: measure resistance between wire and engine metal or
ground. If resistance is below 100000 (100K) ohms, then the wire is shorted to ground and
must be repaired.
2 Continuity.
· Continuity check: measure resistance between ends of same wire. If resistance is more
than 10 ohms, then the wire must be repaired.
NOTE: An incorrectly wired harness can cause this problem. When you test these circuits,
make sure the contacts are installed in the correct positions in each connector as
specified in the wiring diagram.
EGT Thermocouple Circuit Channel B Harness
JUNCTION BOX-EGT (4012KS5) EEC (4000KS)
(4012KS5-B) (4000KS-J10)
Contacts Contacts
Chromel lug (smaller) Y
Alumel lug (larger) B
3 If a problem is found with the harness, repair as necessary or replace the core EGT
harness and Ref. ASM 73-25-15.
(f) Install all removed connectors Ref. AMM 70-23-15-912-010 .
(g) Do the test for this fault, listed in Para 3. for fault confirmation.
1 If the test does not give the fault acronym T5L, send the engine back to service.
2 If the fault continues, remove and replace the EEC ( 4000KS ) Ref.
AMM 73-22-34-000-010 and Ref. AMM 73-22-34-400-010 .
Subtask 77-20-00-810-091-A
B. Fault Isolation for Fault Acronym T5XCF
· The EGT thermocouple signal does not agree with the signal from the opposite channel. This
crosscheck fault (XCF) is caused by an open, short to ground or a wire to wire short in this circuit. This
fault will always be set in both channels.
NOTE: After each step that is done during this procedure, you can do the steps in Para 3. to make sure
the fault is corrected.
NOTE: Disconnection and connection of the electrical connectors can correct this fault.
(1) Do the steps that follow:
(a) Visually examine the harness from the channel A EEC connector (4000KS-J4) to the junction
BOX-EGT (4012KS5) Ref. AMM 71-50-00-210-010 .
1 Look for harness damage.
2 Look for loose or damaged connectors.
3 Look for loose or damaged backshells.
NOTE: Loose backshells must be disassembled and examined for internal wiring chafing.
4 If a problem is found with the harness, repair as necessary or replace the core EGT
harness and Ref. ASM 73-25-15.
(b) Visually examine the harness from the channel B EEC connector (4000KS-J10) to the junction
BOX-EGT (4012KS5) Ref. AMM 71-50-00-210-010 .
1 Look for harness damage.
2 Look for loose or damaged connectors.
3 Look for loose or damaged backshells.
NOTE: Loose backshells must be disassembled and examined for internal wiring chafing.
4 If a problem is found with the harness, repair as necessary or replace the core EGT
harness and Ref. ASM 73-25-15.
(c) Visually examine the harness between the junction BOX-EGT (4012KS5) and the thermocouple-
EGT 1 to 4 (4012KS1, 4012KS2, 4012KS3, 4012KS4) Ref. AMM 71-50-00-210-010 and Ref.
ASM 73-25-15.
1 Look for harness damage.
2 If a problem is found with the harness, repair as necessary or replace the EGT harness
Ref. AMM 77-21-43-000-010 and Ref. AMM 77-21-43-400-010 and Ref. ASM 73-25-15.
3 If moisture is found on the EGT harness or junction box, you can apply NITROGEN
COMPRESSED SOURCE - GROUND or HOT AIR SOURCE, or the harness can be
restored by the bake procedure in the vendor CMM.
(Ref. Fig. Direction of Nitrogen or Hot Air for Dry Out of Junction box SHEET 1)
(d) Do the functional test of the EGT harness, junction box and thermocouples Ref.
AMM 77-21-43-700-010 .
1 Repair or replace if necessary the EGT harness Ref. AMM 77-21-43-000-010 and Ref.
AMM 77-21-43-400-010 .
2 Replace if necessary the EGT thermocouples Ref. AMM 77-21-15-000-010 and Ref.
AMM 77-21-15-400-010 .
3 Replace if necessary the JUNCTION BOX-EGT ( 4012KS5 ) Ref. AMM 77-21-43-000-010
and Ref. AMM 77-21-43-400-010 .
(e) If no problems were found, disconnect electrical connector (4000KS-J4) from the
EEC ( 4000KS ) . Examine the male and female parts of the connection Ref.
AMM 71-50-00-210-010 .
1 Examine pins and sockets (contacts) for alignment and damage.
2 Look for contacts pushed rearward into the connector face.
3 Look for ovalized sockets in the connector.
NOTE: This can be done by inserting a harness connector pin into each socket. You must
feel friction when you insert and remove the pin.
4 Repair as necessary.
(f) Do this electrical check of the harness in channel A. Look for:
1 Wire to wire shorts and shorts to ground.
· Wire to wire short check: measure resistance between wires. If resistance is below
100000 (100K) ohms, then the wires are shorted and must be repaired.
· Wire to ground short check: measure resistance between wire and engine metal or
ground. If resistance is below 100000 (100K) ohms, then the wire is shorted to ground and
must be repaired.
2 Continuity.
· Continuity check: measure resistance between ends of same wire. If resistance is more
than 10 ohms, then the wire must be repaired.
NOTE: An incorrectly wired harness can cause this problem. When you test these circuits,
make sure the contacts are installed in the correct positions in each connector as
specified in the wiring diagram.
EGT Thermocouple Circuit Channel A Harness
JUNCTION BOX-EGT (4012KS5) EEC (4000KS)
(4012KS5-A) (4000KS-J4)
Contacts Contacts
Chromel lug (smaller) Y
Alumel lug (larger) B
3 If a problem is found with the harness, repair as necessary or replace the core EGT
harness and Ref. ASM 73-25-15.
(g) If no problems were found, disconnect electrical connector (4000KS-J10) from
the EEC ( 4000KS ) . Examine the male and female parts of the connection Ref.
AMM 71-50-00-210-010 .
1 Examine pins and sockets (contacts) for alignment and damage.
2 Look for contacts pushed rearward into the connector face.
3 Look for ovalized sockets in the connector.
NOTE: This can be done by inserting a harness connector pin into each socket. You must
feel friction when you insert and remove the pin.
4 Repair as necessary.
(h) Do this electrical check of the harness in channel B. Look for:
1 Wire to wire shorts and shorts to ground.
· Wire to wire short check: measure resistance between wires. If resistance is below
100000 (100K) ohms, then the wires are shorted and must be repaired.
· Wire to ground short check: measure resistance between wire and engine metal or
ground. If resistance is below 100000 (100K) ohms, then the wire is shorted to ground and
must be repaired.
2 Continuity.
· Continuity check: measure resistance between ends of same wire. If resistance is more
than 10 ohms, then the wire must be repaired.
NOTE: An incorrectly wired harness can cause this problem. When you test these circuits,
make sure the contacts are installed in the correct positions in each connector as
specified in the wiring diagram.
EGT Thermocouple Circuit Channel B Harness
JUNCTION BOX-EGT (4012KS5) EEC (4000KS)
(4012KS5-B) (4000KS-J10)
Contacts Contacts
Chromel lug (smaller) Y
Alumel lug (larger) B
3 If a problem was found with the harness, repair as necessary or replace the core EGT
harness and Ref. ASM 73-25-15.
(i) Install all removed connectors Ref. AMM 70-23-15-912-010 .
(j) Do the test for this fault, listed in Para 3. for fault confirmation.
1 If the test does not give the fault acronym T5XCF, send the engine back to service.
2 If this fault continues, remove and replace the EEC ( 4000KS ) Ref.
AMM 73-22-34-000-010 and Ref. AMM 73-22-34-400-010 .
5. Close-up
Subtask 77-20-00-860-055-A
A. Put the aircraft back to its initial configuration.
(1) Make sure that the thrust reverser halves 461AL and 462AR are closed Ref.
AMM 78-32-00-410-010 .
(2) Activate the thrust reverser HCU Ref. AMM 78-30-00-440-012 .
(3) Make sure that the fan cowls 447AL and 448AR are closed Ref. AMM 71-13-00-410-010 .
(4) On the ECAM control panel, set the UPPER DISPLAY and LOWER DISPLAY potentiometers to OFF
Ref. AMM 31-60-00-860-002 .
(5) On the ENG section of the maintenance panel 50VU, push the FADEC GND PWR 2 pushbutton
switch.
(6) De-energize the aircraft electrical circuits Ref. AMM 24-41-00-862-002 .
(7) Remove the warning notice(S).
Figure 77(IAE)-20-00-991-00100-13-A- / SHEET 1/1 - EGT Indication Circuit
Figure 77(IAE)-20-00-991-00300-13-A- / SHEET 1/1 - Direction of Nitrogen or Hot Air for Dry Out of Junction box
77-30 - (IAE) - ANALYZERS
77-30-00 - (IAE) - ANALYZERS
77-30-00 PB 201 CONF 13 - ANALYZERS - FAULT ISOLATION PROCEDURES [Rev.6 from Feb 2017] 2026.04.04 04:37:51 UTC