DOC AIRBUS | TSM A320FL(R) Low Level Sensor 40QJ1(2)
TASK 28-46-00-810-816-A
L(R) Low Level Sensor 40QJ1(2)
A. Referenced Information
3. Fault Confirmation
Subtask 28-46-00-740-065-A ** ON A/C NOT FOR ALL
Subtask 28-46-00-810-065-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:29:16 UTC
L(R) Low Level Sensor 40QJ1(2)
WARNING:
OBEY THE FUEL SAFETY PROCEDURES.
WARNING:
WHEN YOU DO WORK ON THE FUEL SYSTEM WIRING, YOU MUST USE TEST EQUIPMENT THAT IS APPROVED (REFER TO INTERNATIONAL OR NATIONAL SPECIFICATIONS FOR INTRINSICALLY SAFE TEST EQUIPMENT: EN50020, UL913 OR EQUIVALENT). TEST EQUIPMENT THAT IS NOT APPROVED CAN CAUSE FIRE OR AN EXPLOSION.
1. Possible Causes- FLSCU-1 [7QJ]
- FLSCU-2 [9QJ]
- aircraft wiring
- HARNESS-LEFT WING TANK A [57QT]
- HARNESS-RIGHT WING, TANK A [58QT]
- SENSOR-LOW LVL (1500KG), L WING TANK CHANNEL A [40QJ1]
- SENSOR-LOW LVL (1500KG), R WING TANK CHANNEL A [40QJ2]
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
| TSM TASK 28-46-00-810-818-A | FLSCU1(2) 7QJ(9QJ) |
| ESPM 2053210 | |
| AMM 28-10-00-910-001 | Safety Procedures When You Do Work in a Fuel Tank |
| AMM 28-10-00-910-002 | Access to the Fuel Tanks and the Work Areas |
| AMM 28-42-43-000-005 | Removal of the Wing Tank Harness |
| AMM 28-42-43-000-008 | Removal of the Wing Tank Fuel Quantity Indicating Probe Fused/Shorting Plug Connectors |
| AMM 28-42-43-400-005 | Installation of the Wing Tank Harness |
| AMM 28-46-00-740-001 | Functional (BITE) Test |
| ASM 284602 | |
| AWM 284604 | |
| AWM 284606 | |
| AMM 28-46-15-000-001 | Removal of the Wing-Tank Fuel-Level Sensors |
| AMM 28-46-15-400-009 | Installation of the Wing-Tank Fuel-Level Sensors |
| AMM 28-46-34-000-001 | Removal of the Fuel-Level Sensing Control-Unit (FLSCU) |
| AMM 28-46-34-400-001 | Installation of the Fuel-Level Sensing Control-Unit (FLSCU) |
Subtask 28-46-00-740-065-A ** ON A/C NOT FOR ALL
A. Test
(1) Do the BITE test of the FLSS AMM 28-46-00-740-001.
(2) Examine the FLSS STATUS page on the MCDU.
(3) If the page shows messages for one or more of the other sensors and/or the FLSCU-1(2), do (Ref. TSM TASK 28-46-00-810-818).
(4) If the message 284615 L(R) LO LEVEL SENSOR 40QJ1(2):
4. Fault Isolation(1) Do the BITE test of the FLSS AMM 28-46-00-740-001.
(2) Examine the FLSS STATUS page on the MCDU.
(3) If the page shows messages for one or more of the other sensors and/or the FLSCU-1(2), do (Ref. TSM TASK 28-46-00-810-818).
(4) If the message 284615 L(R) LO LEVEL SENSOR 40QJ1(2):
- is shown, do Para. 4.A.
- is not shown, no work steps are necessary.
NOTE: You can get more data from the:
- Aircraft Maintenance Manual (AMM) Chap. 28-46-00, the Fuel Level Sensing System, Description and Operation (D and O)
- Trouble Shooting Manual (TSM) - Task Supporting Data (Ref. P. Block 301)
- Aircraft Schematic Manual (ASM) ASM 284602.
- Input Parameters Page 3 (Ref. P. Block 301), used with the Fuel Level Sensors Operating (Changeover) Values (Ref. P. Block 301)
- Trouble-shooting Data (Ref. P. Block 301).
NOTE: OPTIONAL TESTING:
Where a PSDA321-1 Test Set is available, a check can be made before a decision is made to go into or close up a fuel tank. The Test Set enables a GO/NOGO check to be made of the tank mounted components and wiring from the tank wall connectors.
Where a PSDA321-1 Test Set is available, a check can be made before a decision is made to go into or close up a fuel tank. The Test Set enables a GO/NOGO check to be made of the tank mounted components and wiring from the tank wall connectors.
Subtask 28-46-00-810-065-A ** ON A/C NOT FOR ALL
A. Procedure
(1) Do the steps applicable to the test equipment available.
(2) Test Equipment.
(4) Disconnect the free connector 4039VC1(2)-A from the receptacle 4039VC1(2).
(5) Do a resistance check of the sensor 40QJ1(2) at the tank wall connector 4039VC1(2) between pins L and M AWM 284604.
Make sure the resistance is between 330 and 480 ohms.
If there is:
(7) If the fault continues:
(a) Get access to the tank wall connector 4039VC1(2)-A (for the wing tank harness 57QT(58QT) AMM 28-42-43-000-008
(b) Disconnect the free connector 4039VC1(2)-A from the receptacle 4039VC1(2).
(c) Do a check AWM 284604 of the aircraft wiring (sensor input line - H) between the FLSCU-1(2) rack connector AB, pin 13A and the tank wall free connector 4039VC1(2)-A, pin L.
(d) Do a check AWM 284604 of the aircraft wiring (sensor input line - L) between the FLSCU-1(2) rack connector AB, pin 13B and the tank wall free connector 4039VC1(2)-A, pin M.
(e) Do a check AWM 284606 of the aircraft wiring (STD2/A321 identify line) between the FLSCU-1(2) rack connector AA, pin 6D, and the DC2 ground/earth point (614VG).
(g) Do a check AWM 284606 of the aircraft wiring (FLSCU-1 LS8 output line) between the FLSCU-1 rack connector AB, pin 4A and the FQIC rack connector AC, pin 3J or the (aircraft wiring (FLSCU-2 LS8 output line) between the FLSCU-2 rack connector AB, pin 4A and the FQIC rack connector AC, pin 1H).
(h) Repair all the unserviceable wiring and connectors ESPM 2053210.
(i) Do the test in Para. 3.A.
(8) If the fault continues or if there is no continuity in Step (5):
(a) Drain, open and vent the tank AMM 28-10-00-910-001 and AMM 28-10-00-910-002.
(b) Do a wiring check of the HARNESS-LEFT WING TANK A [57QT] , ( HARNESS-RIGHT WING, TANK A [58QT] ) AWM 284604 and replace, if necessary AMM 28-42-43-000-005 and AMM 28-42-43-400-005.
(c) If the harness is serviceable, replace the SENSOR-LOW LVL (1500KG), L WING TANK CHANNEL A [40QJ1] ( SENSOR-LOW LVL (1500KG), R WING TANK CHANNEL A [40QJ2] ) AMM 28-46-15-000-001 and AMM 28-46-15-400-009.
(1) Do the steps applicable to the test equipment available.
(2) Test Equipment.
WARNING:
WHEN YOU DO WORK ON THE FUEL SYSTEM WIRING, YOU MUST USE TEST EQUIPMENT THAT IS APPROVED (REFER TO INTERNATIONAL OR NATIONAL SPECIFICATIONS FOR INTRINSICALLY SAFE TEST EQUIPMENT: EN50020, UL913 OR EQUIVALENT). TEST EQUIPMENT THAT IS NOT APPROVED CAN CAUSE FIRE OR AN EXPLOSION.
(a) If there is: - approved test equipment available, go to Step (3)
- no approved test equipment available, go to Step (6).
(4) Disconnect the free connector 4039VC1(2)-A from the receptacle 4039VC1(2).
(5) Do a resistance check of the sensor 40QJ1(2) at the tank wall connector 4039VC1(2) between pins L and M AWM 284604.
Make sure the resistance is between 330 and 480 ohms.
If there is:
- continuity as specified above, go to Step (6)
- no continuity as specified above (resistance check out of range), go to Step (8).
NOTE: The sensor status (wet or dry) and fuel/air temperature will have an effect on the resistance value.
(6) Replace the FLSCU-1 [7QJ] ( FLSCU-2 [9QJ] ) AMM 28-46-34-000-001 and AMM 28-46-34-400-001. (7) If the fault continues:
(a) Get access to the tank wall connector 4039VC1(2)-A (for the wing tank harness 57QT(58QT) AMM 28-42-43-000-008
(b) Disconnect the free connector 4039VC1(2)-A from the receptacle 4039VC1(2).
(c) Do a check AWM 284604 of the aircraft wiring (sensor input line - H) between the FLSCU-1(2) rack connector AB, pin 13A and the tank wall free connector 4039VC1(2)-A, pin L.
(d) Do a check AWM 284604 of the aircraft wiring (sensor input line - L) between the FLSCU-1(2) rack connector AB, pin 13B and the tank wall free connector 4039VC1(2)-A, pin M.
(e) Do a check AWM 284606 of the aircraft wiring (STD2/A321 identify line) between the FLSCU-1(2) rack connector AA, pin 6D, and the DC2 ground/earth point (614VG).
NOTE: The level sense channel 8 (LS8) of FLSCU-1(2) is only used on STD2/A321 aircraft fitted with a Simmonds FQIC.
The fault message L(R) LO LEVEL SENSOR 40QJ1(2) will always be shown after the FLSS BITE test if the ground/earth (channel 8 enable) is not supplied to the FLSCU when in this configuration.
(f) Do a check AWM 284606 of the aircraft wiring (FLSCU-1 BITE 2 test command line) between the FLSCU-1 rack connector AA, pin 15A and the FQIC rack connector AB, pin 14E or the (aircraft wiring (FLSCU-2 BITE 2 test command line) between the FLSCU-2 rack connector AA, pin 15A and the FQIC rack connector AB, pin 12E). The fault message L(R) LO LEVEL SENSOR 40QJ1(2) will always be shown after the FLSS BITE test if the ground/earth (channel 8 enable) is not supplied to the FLSCU when in this configuration.
(g) Do a check AWM 284606 of the aircraft wiring (FLSCU-1 LS8 output line) between the FLSCU-1 rack connector AB, pin 4A and the FQIC rack connector AC, pin 3J or the (aircraft wiring (FLSCU-2 LS8 output line) between the FLSCU-2 rack connector AB, pin 4A and the FQIC rack connector AC, pin 1H).
(h) Repair all the unserviceable wiring and connectors ESPM 2053210.
(i) Do the test in Para. 3.A.
(8) If the fault continues or if there is no continuity in Step (5):
(a) Drain, open and vent the tank AMM 28-10-00-910-001 and AMM 28-10-00-910-002.
(b) Do a wiring check of the HARNESS-LEFT WING TANK A [57QT] , ( HARNESS-RIGHT WING, TANK A [58QT] ) AWM 284604 and replace, if necessary AMM 28-42-43-000-005 and AMM 28-42-43-400-005.
(c) If the harness is serviceable, replace the SENSOR-LOW LVL (1500KG), L WING TANK CHANNEL A [40QJ1] ( SENSOR-LOW LVL (1500KG), R WING TANK CHANNEL A [40QJ2] ) AMM 28-46-15-000-001 and AMM 28-46-15-400-009.