Loss of the feedback signal from the TBV valve through the two channels on Engine 1

TASK 75-26-00-810-813-A
Loss of the feedback signal from the TBV valve through the two channels on Engine 1

1. Possible Causes

ECU [4000KS]
harness HJ11
harness HJ12
harness CJ11L
harness CJ12L
TBV valve

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-50-000-025	Removal of the CJ11L Harness
AMM 73-21-50-000-027	Removal of the CJ12L Harness
AMM 73-21-50-000-044	Removal of the HJ11 Harness for SAC Engines
AMM 73-21-50-000-045	Removal of the HJ12 Harness for SAC Engines
AMM 73-21-50-210-002	Visual Inspection of the Wiring Harnesses
AMM 73-21-50-400-025	Installation of the CJ11L Harness
AMM 73-21-50-400-027	Installation of the CJ12L Harness
AMM 73-21-50-400-044	Installation of the HJ11 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 75-26-10-000-001	Removal of the Transient Bleed Valve
AMM 75-26-10-400-001	Installation of the Transient Bleed Valve

3. Fault Confirmation
Subtask 75-26-00-710-074-A ** ON A/C NOT FOR ALL

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

4. Fault Isolation
Subtask 75-26-00-810-062-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message TBV VLV, J11, ECU and TBV VLV, J12, ECU:

Disconnect the HJ11 and HJ12 harnesses fron the J11 and J12 receptacles on the ECU (4000KS). Make sure that the electrical contacts of the J11 and J12 receptacles are not bent or have not moved AMM 73-21-50-210-002.

(1) If you find damage:

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

(2) Do a resistance check of the TBV valve circuits through the HJ11 and HJ12 harnesses, between:
. pins 40 and 41 (1 to 150 Ohms)
. pins 20 and 39 (1 to 150 Ohms)
. pins 8 and 22 (1 to 150 Ohms)
. pins 40 and 21 (> 10 Megohms)
. pins 20 and 21 (> 10 Megohms)
. pins 8 and 21 (> 10 Megohms)
. pin 40 and the ground (> 10 Megohms)
. pin 20 and the ground (> 10 Megohms)
. pin 8 and the ground (> 10 Megohms).
(a) 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.

(b) If the resistance values are out of the specified limits:

disconnect the cables HJ11 and HJ12 from the cables CJ11L and CJ12L at the 6 o' clock junction box and do a resistance check through the CJ11L and CJ12L harnesses between:
for cable CJ11L
. pins 8 and 10 (1 to 150 Ohms)
. pins 11 and 12 (1 to 150 Ohms)
. pins 13 and 14 (1 to 150 Ohms)
. pins 8 and 9 (> 10 Megohms)
. pins 11 and 9 (> 10 Megohms)
. pins 13 and 9 (> 10 Megohms)
. pin 8 and the ground (> to Megohms)
. pin 11 and the ground (> 10 Megohms)
. pin 13 and the ground (> 10 Megohms)
for cable CJ12L
. pins 2 and 3 (1 to 150 Ohms)
. pins 4 and 5 (1 to 150 Ohms)
. pins 12 and 13 (1 to 150 Ohms)
. pins 2 and 1 (> 10 Megohms)
. pins 4 and 1 (> 10 Megohms)
. pins 12 and 1 (> 10 Megohms)
. pin 2 and ground (> to Megohms)
. pin 4 and ground (> 10 Megohms)
. pin 12 and ground (> 10 Megohms).

1 If the resistance values are in the specified limits:

replace the defective harness HJ11 AMM 73-21-50-000-044 and AMM 73-21-50-400-044 or harness HJ12 AMM 73-21-50-000-045 and AMM 73-21-50-400-045.

2 If the resistance values are out of the specified limits:

disconnect the cables CJ11L and CJ12L from the TBV valve and do a resistance check of the TBV valve between:
. pins 2 and 3 (1 to 150 Ohms)
. pins 4 and 5 (1 to 150 Ohms)
. pins 6 and 7 (1 to 150 Ohms)
. pin 2 and the ground (> 10 Megohms)
. pin 4 and the ground (> 10 Megohms)
. pin 6 and the ground (> 10 Megohms)

a If the resistance values are in the specified limits:

replace the defective: harness CJ11L AMM 73-21-50-000-025 and AMM 73-21-50-400-025 or harness CJ12L AMM 73-21-50-000-027 and AMM 73-21-50-400-027.

b If the resistance values are out of the specified limits:

replace the TBV valve AMM 75-26-10-000-001 and AMM 75-26-10-400-001.

(3) Connect the disconnected harnesses.

Subtask 75-26-00-710-075-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.A.

[Rev.8 from Aug 2018] 2026.04.04 04:37:06 UTC