Loss of the feedback Signal from the VBV through the two Channels on Engine 1

TASK 75-30-00-810-811-A
Loss of the feedback Signal from the VBV through the two Channels on Engine 1

1. Possible Causes

VBV sensor (RVDT)
ECU [4000KS]
harness J11
harness J12
harness CJ11L
harness CJ12L

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-50-000-001	Removal of the CJ11L Harness
AMM 73-21-50-000-003	Removal of the CJ12L Harness
AMM 73-21-50-000-010	Removal of the J11 Harness
AMM 73-21-50-000-011	Removal of the J12 Harness
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 73-21-50-400-001	Installation of the CJ11L Harness
AMM 73-21-50-400-003	Installation of the CJ12L Harness
AMM 73-21-50-400-010	Installation of the J11 Harness
AMM 73-21-50-400-011	Installation of the J12 Harness
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)
ASM 732518
AMM 73-29-00-710-040	Operational Test of the FADEC on the ground (with Engine Motoring)
AMM 75-31-70-000-001	Removal of the Variable Bleed Valve Position Sensor
AMM 75-31-70-000-002	Removal of the Variable Bleed Valve position Sensor
AMM 75-31-70-400-001	Installation of the Variable Bleed Valve Position Sensor
AMM 75-31-70-400-002	Installation of the Variable Bleed Valve position Sensor

3. Fault Confirmation
Subtask 75-30-00-710-072-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 75-30-00-810-061-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance messages VBV SENS, J11, ECU + VBV SENS, J12, ECU:

do a check for open or short to ground of the harnesses J11 and J12 between the ECU (4000KS) and the 6 o'clock junction box, between the 6 o'clock juntion box and the VBV sensor (RVDT) ASM 732518.

(1) If one of these wirings is not correct:

repair the defective above wirings.

(2) If these wirings are correct:

disconnect the cables J11 (Channel A) and J12 (Channel B) from the ECU (4000KS) and do a resistance check of the cables J11 and J12 between:
. pins 13 and 29 (80 to 110 Ohms)
. pins 30 and 31 (80 to 120 Ohms)
. pins 15 and 32 (80 to 120 Ohms)
. pins 13 and 14 (> 10 Megohms)
. pins 30 and 14 (> 10 Megohms)
. pins 15 and 14 (> 10 Megohms)
. pin 13 and the ground (> 10 Megohms)
. pin 30 and the ground (> 10 Megohms)
. pin 15 and the ground (> 10 Megohms).

(a) If the resistance values are in the specified limits:

replace the VBV sensor (RVDT) AMM 75-31-70-000-001 and AMM 75-31-70-400-001.
if the problem is still reported after the VBV sensor replacement, 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 J11 and J12 from the cables CJ11L and CJ12L at the 6 o'clock junction box and do a resistance check of the cables CJ11L and CJ12L between:
for cable CJ11L
. pins 5 and 6 (80 to 110 Ohms)
. pins 2 and 7 (80 to 120 Ohms)
. pins 3 and 4 (80 to 120 Ohms)
. pins 5 and 1 (> 10 Megohms)
. pins 2 and 1 (> 10 Megohms)
. pins 3 and 1 (> 10 Megohms)
. pin 5 and the ground (> 10 Megohms)
. pin 2 and the ground (> 10 Megohms)
. pin 3 and the ground (> 10 Megohms).
for cable CJ12L
. pins 17 and 6 (80 to 110 Ohms)
. pins 18 and 19 (80 to 120 Ohms)
. pins 8 and 20 (80 to 120 Ohms)
. pins 17 and 7 (> 10 Megohms)
. pins 18 and 7 (> 10 Megohms)
. pins 8 and 7 (> 10 Megohms)
. pin 17 and the ground (> 10 Megohms)
. pin 18 and the ground (> 10 Megohms)
. pin 8 and the ground (> 10 Megohms).

1 If the resistance values are in the specified limits:

replace the defective harness J11 AMM 73-21-50-000-010 and AMM 73-21-50-400-010 or harness J12 AMM 73-21-50-000-011 and AMM 73-21-50-400-011.

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

disconnect the cables CJ11L and CJ12L from the VBV sensor and do a resistance check of the VBV sensor between:
. pins 2 and 3 (80 to 110 Ohms)
. pins 4 and 5 (80 to 120 Ohms)
. pins 6 and 7 (80 to 120 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 73-21-50-000-001 and AMM 73-21-50-400-001 or harness CJ12L AMM 73-21-50-000-003 and AMM 73-21-50-400-003.

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

replace the VBV sensor (RVDT) AMM 75-31-70-000-001 and AMM 75-31-70-400-001.

Subtask 75-30-00-810-061-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance messages VBV SNSR, J11, ECU + VBV SNSR, J12, ECU:

do a check for open or short to ground of the harnesses J11 and J12 between the ECU (4000KS) and the 6 o'clock junction box, between the 6 o'clock juntion box and the VBV sensor (RVDT) ASM 732518.

(1) If one of these wirings is not correct:

repair the defective above wirings.

(2) If these wirings are correct:

disconnect the cables J11 (Channel A) and J12 (Channel B) from the ECU (4000KS) and do a resistance check of the cables J11 and J12 between:
. pins 13 and 29 (80 to 110 Ohms)
. pins 30 and 31 (80 to 120 Ohms)
. pins 15 and 32 (80 to 120 Ohms)
. pins 13 and 14 (> 10 Megohms)
. pins 30 and 14 (> 10 Megohms)
. pins 15 and 14 (> 10 Megohms)
. pin 13 and the ground (> 10 Megohms)
. pin 30 and the ground (> 10 Megohms)
. pin 15 and the ground (> 10 Megohms).

(a) If the resistance values are in the specified limits:

replace the VBV sensor (RVDT) AMM 75-31-70-000-001 and AMM 75-31-70-400-001.
if the problem is still reported after the VBV sensor replacement, 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 J11 and J12 from the cables CJ11L and CJ12L at the 6 o'clock junction box and do a resistance check of the cables CJ11L and CJ12L between:
for cable CJ11L
. pins 5 and 6 (80 to 110 Ohms)
. pins 2 and 7 (80 to 120 Ohms)
. pins 3 and 4 (80 to 120 Ohms)
. pins 5 and 1 (> 10 Megohms)
. pins 2 and 1 (> 10 Megohms)
. pins 3 and 1 (> 10 Megohms)
. pin 5 and the ground (> 10 Megohms)
. pin 2 and the ground (> 10 Megohms)
. pin 3 and the ground (> 10 Megohms).
for cable CJ12L
. pins 17 and 6 (80 to 110 Ohms)
. pins 18 and 19 (80 to 120 Ohms)
. pins 8 and 20 (80 to 120 Ohms)
. pins 17 and 7 (> 10 Megohms)
. pins 18 and 7 (> 10 Megohms)
. pins 8 and 7 (> 10 Megohms)
. pin 17 and the ground (> 10 Megohms)
. pin 18 and the ground (> 10 Megohms)
. pin 8 and the ground (> 10 Megohms).

1 If the resistance values are in the specified limits:

replace the defective harness J11 AMM 73-21-50-000-010 and AMM 73-21-50-400-010 or harness J12 AMM 73-21-50-000-011 and AMM 73-21-50-400-011.

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

disconnect the cables CJ11L and CJ12L from the VBV sensor and do a resistance check of the VBV sensor between:
. pins 2 and 3 (80 to 110 Ohms)
. pins 4 and 5 (80 to 120 Ohms)
. pins 6 and 7 (80 to 120 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 73-21-50-000-001 and AMM 73-21-50-400-001 or harness CJ12L AMM 73-21-50-000-003 and AMM 73-21-50-400-003.

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

replace the VBV sensor (RVDT) AMM 75-31-70-000-001 and AMM 75-31-70-400-001.

Subtask 75-30-00-810-061-C ** ON A/C NOT FOR ALL

A. If the test gives the maintenance messages VBV SNSR, J11, ECU + VBV SNSR, J12, ECU:

do a check for open or short to ground of the harnesses J11 and J12 between the ECU (4000KS) and the 6 o'clock junction box, between the 6 o'clock juntion box and the VBV sensor (RVDT) ASM 732518.

(1) If one of these wirings is not correct:

repair the defective above wirings.

(2) If these wirings are correct:

disconnect the cables J11 (Channel A) and J12 (Channel B) from the ECU (4000KS) and do a resistance check of the cables J11 and J12 between:
. pins 13 and 29 (80 to 110 Ohms)
. pins 30 and 31 (80 to 120 Ohms)
. pins 15 and 32 (80 to 120 Ohms)
. pins 13 and 14 (> 10 Megohms)
. pins 30 and 14 (> 10 Megohms)
. pins 15 and 14 (> 10 Megohms)
. pin 13 and the ground (> 10 Megohms)
. pin 30 and the ground (> 10 Megohms)
. pin 15 and the ground (> 10 Megohms).

(a) If the resistance values are in the specified limits:

replace the VBV sensor (RVDT) AMM 75-31-70-000-001 and AMM 75-31-70-400-001.
if the problem is still reported after the VBV sensor replacement, 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 J11 and J12 from the cables CJ11L and CJ12L at the 6 o'clock junction box and do a resistance check of the cables CJ11L and CJ12L between:
for cable CJ11L
. pins 5 and 6 (80 to 110 Ohms)
. pins 2 and 7 (80 to 120 Ohms)
. pins 3 and 4 (80 to 120 Ohms)
. pins 5 and 1 (> 10 Megohms)
. pins 2 and 1 (> 10 Megohms)
. pins 3 and 1 (> 10 Megohms)
. pin 5 and the ground (> 10 Megohms)
. pin 2 and the ground (> 10 Megohms)
. pin 3 and the ground (> 10 Megohms).
for cable CJ12L
. pins 17 and 6 (80 to 110 Ohms)
. pins 18 and 19 (80 to 120 Ohms)
. pins 8 and 20 (80 to 120 Ohms)
. pins 17 and 7 (> 10 Megohms)
. pins 18 and 7 (> 10 Megohms)
. pins 8 and 7 (> 10 Megohms)
. pin 17 and the ground (> 10 Megohms)
. pin 18 and the ground (> 10 Megohms)
. pin 8 and the ground (> 10 Megohms).

1 If the resistance values are in the specified limits:

replace the defective harness J11 AMM 73-21-50-000-044 and AMM 73-21-50-400-044 or harness J12 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 VBV sensor and do a resistance check of the VBV sensor between:
. pins 2 and 3 (80 to 110 Ohms)
. pins 4 and 5 (80 to 120 Ohms)
. pins 6 and 7 (80 to 120 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 VBV sensor (RVDT) AMM 75-31-70-000-002 and AMM 75-31-70-400-002.

Subtask 75-30-00-710-073-A ** ON A/C NOT FOR ALL

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

[Rev.8 from Aug 2018] 2026.04.04 04:37:07 UTC