Loss of the feedback signal from the TBV valve through the channel A on Engine 1

TASK 75-26-00-810-801-A
Loss of the feedback signal from the TBV valve through the channel A on Engine 1

1. Possible Causes

ECU [4000KS]
harness HJ11
harness CJ11L
Transient Bleed Valve (TBV)

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-50-000-025	Removal of the CJ11L Harness
AMM 73-21-50-000-044	Removal of the HJ11 Harness for SAC Engines
AMM 73-21-50-400-025	Installation of the CJ11L Harness
AMM 73-21-50-400-044	Installation of the HJ11 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 75-26-00-710-050-A ** ON A/C NOT FOR ALL

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

4. Fault Isolation
Subtask 75-26-00-810-050-A ** ON A/C NOT FOR ALL

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

disconnect the HJ11 harness from the J11 receptacle on the ECU (4000KS). Make sure that the electrical contacts of the J11 receptacle are not bent or have not moved.

(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 (channel A), through HJ11 and CJ11L 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 (more than 10 Megohms)
. pins 20 and 21 (more than 10 Megohms)
. pins 8 and 21 (more than 10 Megohms)
. pin 40 and the ground (more than 10 Megohms)
. pin 20 and the ground (more than 10 Megohms)
. pin 8 and the ground (more than 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 cable HJ11 from the cable CJ11L at the 6 o'clock junction box and do a resistance check of the RACSB valve circuits (channel A), through the CJ11L harness between:
. 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 (more than 10 Megohms)
. pins 11 and 9 (more than 10 Megohms)
. pins 13 and 9 (more than 10 Megohms)
. pin 8 and the ground (more than 10 Megohms)
. pin 11 and the ground (more than 10 Megohms)
. pin 13 and the ground (more than 10 Megohms)

1 If the resistance values are in the specified limits:

replace the harness HJ11 AMM 73-21-50-000-044 and AMM 73-21-50-400-044.

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

disconnect the CJ11L harness from the TBV valve and do a resistance check of the TBV valve circuits (channel A) 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 Ground (more than 10 Megohms)
. pin 4 and Ground (more than 10 Megohms)
. pin 6 and Ground (more than 10 Megohms).

a If the resistance values are in the specified limits:

replace the harness CJ11L AMM 73-21-50-000-025 and AMM 73-21-50-400-025.

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

replace the Transient Bleed Valve (TBV) AMM 75-26-10-000-001 and AMM 75-26-10-400-001.

(3) Connect the disconnected harnesses.

Subtask 75-26-00-710-051-A ** ON A/C NOT FOR ALL

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

[Rev.8 from Aug 2018] 2026.04.04 04:37:05 UTC