Loss of the Feedback Signal on the Channel B of the HPTCC Valve on Engine 2

TASK 75-21-00-810-812-A
Loss of the Feedback Signal on the Channel B of the HPTCC Valve on Engine 2

1. Possible Causes

High Pressure Turbine Clearance Control (HPTCC) Valve
ECU [4000KS]
harness J12
harness CJ12R
harness HJ12

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-50-000-004	Removal of the CJ12R Harness
AMM 73-21-50-000-011	Removal of the J12 Harness
AMM 73-21-50-000-028	Removal of the CJ12R Harness for SAC Engines
AMM 73-21-50-000-045	Removal of the HJ12 Harness for SAC Engines
AMM 73-21-50-400-004	Installation of the CJ12R Harness
AMM 73-21-50-400-011	Installation of the J12 Harness
AMM 73-21-50-400-028	Installation of the CJ12R Harness for SAC Engines
AMM 73-21-50-400-045	Installation of the HJ12 Harness for SAC Engines
AMM 73-21-60-000-001	Removal of the Electronic Control Unit (ECU)
AMM 73-21-60-400-001	Installation of the Electronic Control Unit (ECU)
AMM 73-29-00-710-040	Operational Test of the FADEC on the ground (with Engine Motoring)
AMM 75-21-10-000-001	Removal of the High Pressure Turbine Active Clearance Control (HPTACC) Valve
AMM 75-21-10-000-002	Removal of the High Pressure Turbine Active Clearance Control (HPTACC) Valve
AMM 75-21-10-400-001	Installation of the High Pressure Turbine Active Clearance Control (HPTACC) Valve
AMM 75-21-10-400-002	Installation of the High Pressure Turbine Active Clearance Control (HPTACC) Valve

3. Fault Confirmation
Subtask 75-21-00-710-072-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the operational test of the FADEC 2 on the ground with engine non motoring AMM 73-29-00-710-040.

4. Fault Isolation
Subtask 75-21-00-810-065-A ** ON A/C NOT FOR ALL

A. This failure message is triggered when there is a disagreement between channels A and B position signal from the HPTCC Valve or the signal is out of range.
(1) If the failure message HPTC VLV, J12, ECU is not confirmed:
(a) No maintenance action required.
(2) If the failure message HPTC VLV, J12, ECU is not confirmed but is repetitive:
(a) Do the following trouble shooting at next maintenance opportunity:

replace the High Pressure Turbine Clearance Control (HPTCC) Valve AMM 75-21-10-000-001 and AMM 75-21-10-400-001.

1 If the fault continues:

replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

NOTE: Tighten the connector by hand plus one eighth of a turn. If necessary use soft nose pliers.

(3) If the failure message HPTC VLV, J12, ECU is confirmed:
(a) Disconnect the harness J12 from the ECU and do a resistance check of the harness J12 between:
. pins 34 and 35 (68 to 102 Ohms)
. pins 18 and 36 (30 to 42 Ohms)
. pins 16 and 33 (22 to 30 Ohms)
. pins 34 and 17 (>10 Megohms)
. pins 18 and 17 (> 10 Megohms)
. pins 16 and 17 (> 10 Megohms)
. pin 34 and the ground (> 10 Megohms)
. pin 18 and the ground (> 10 Megohms)
. pin 16 and the ground (> 10 Megohms).
1 If the resistance values are in the specified limits:

replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

2 If the resistance values are not in the specified limits:

disconnect the harness CJ12R from the HPTCC Valve and do a resistance check of the HPTCC Valve between:
. pins 2 and 3 (68 to 102 Ohms)
. pins 4 and 5 (30 to 42 Ohms)
. pins 6 and 7 (22 to 30 Ohms)
. pin 2 and the ground (> 10 Megohms)
. pin 4 and the ground (> 10 Megohms)
. pin 6 and the ground (> 10 Megohms).

3 If the resistance values are not in the specified limits:

replace the High Pressure Turbine Clearance Control (HPTCC) Valve AMM 75-21-10-000-001 and AMM 75-21-10-400-001.

4 If the resistance values are in the specified limits:

disconnect the harness J12 from the harness CJ12R at the 6 o'clock junction box and do a check of the resistance of the harness CJ12R between:
. pins 17 and 6 (68 to 102 ohms)
. pins 19 and 18 (30 to 42 ohms)
. pins 20 and 8 (22 to 30 ohms)
. pins 17 and 7 (> 10 Megohms)
. pins 19 and 7 (> 10 Megohms)
. pins 20 and 7 (> 10 Megohms)
. pin 17 and the ground (> 10 Megohms)
. pin 19 and the ground (> 10 Megohms)
. pin 20 and the ground (> 10 Megohms).

a If the resistance values are in the specified limits:

replace the harness J12 AMM 73-21-50-000-011 and AMM 73-21-50-400-011.

b If the resistance values are not in the specified limits:

replace the harness CJ12R AMM 73-21-50-000-004 and AMM 73-21-50-400-004.

NOTE: Tighten the connector by hand plus one eighth of a turn. If necessary use soft nose pliers.

Subtask 75-21-00-810-065-B ** ON A/C NOT FOR ALL

replace the High Pressure Turbine Clearance Control (HPTCC) Valve AMM 75-21-10-000-002 and AMM 75-21-10-400-002.

1 If the fault continues:

replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

NOTE: Tighten the connector by hand plus one eighth of a turn. If necessary use soft nose pliers.

(3) If the failure message HPTC VLV, J12, ECU is confirmed:
(a) Disconnect the harness HJ12 from the ECU and do a resistance check of the harness HJ12 between:
. pins 34 and 35 (68 to 102 Ohms)
. pins 18 and 36 (30 to 42 Ohms)
. pins 16 and 33 (22 to 30 Ohms)
. pins 34 and 17 (> 10 Megohms)
. pins 18 and 17 (> 10 Megohms)
. pins 16 and 17 (> 10 Megohms)
. pin 34 and the ground (> 10 Megohms)
. pin 18 and the ground (> 10 Megohms)
. pin 16 and the ground (> 10 Megohms).
1 If the resistance values are in the specified limits:

replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

2 If the resistance values are not in the specified limits:

disconnect the harness CJ12R from the HPTCC Valve and do a resistance check of the HPTCC Valve between:
. pins 2 and 3 (65 to 99 Ohms)
. pins 4 and 5 (23 to 40 Ohms)
. pins 6 and 7 (18 to 29 Ohms)
. pin 2 and the ground (> 10 Megohms)
. pin 4 and the ground (> 10 Megohms)
. pin 6 and the ground (> 10 Megohms).

3 If the resistance values are not in the specified limits:

replace the High Pressure Turbine Clearance Control (HPTCC) Valve AMM 75-21-10-000-002 and AMM 75-21-10-400-002.

4 If the resistance values are in the specified limits:

disconnect the harness HJ12 from the harness CJ12R at the 6 o'clock junction box and do a check of the resistance of the harness CJ12R between:
. pins 17 and 6 (68 to 102 ohms)
. pins 19 and 18 (30 to 42 ohms)
. pins 20 and 8 (22 to 30 ohms)
. pins 17 and 7 (> 10 Megohms)
. pins 19 and 7 (> 10 Megohms)
. pins 20 and 7 (> 10 Megohms)
. pin 17 and the ground (> 10 Megohms)
. pin 19 and the ground (> 10 Megohms)
. pin 20 and the ground (> 10 Megohms).

a If the resistance values are in the specified limits:

replace the harness HJ12 AMM 73-21-50-000-045 and AMM 73-21-50-400-045.

b If the resistance values are not in the specified limits:

replace the harness CJ12R AMM 73-21-50-000-028 and AMM 73-21-50-400-028.

NOTE: Tighten the connector by hand plus one eighth of a turn. If necessary use soft nose pliers.

Subtask 75-21-00-710-073-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.
(1) No additional maintenance action is required if the fault is not confirmed.
(2) Continue the fault isolation procedure if the fault continues.

[Rev.8 from Aug 2018] 2026.04.04 04:37:02 UTC