DOC AIRBUS | TSM A320FLoss of Weight on Wheels Signal on the System 1
1. Possible Causes
· PROX SNSR-R L/G EXT, SYS 1 ( 20GA )
· PROX SNSR-L L/G EXT, SYS 1 ( 21GA )
· LGCIU-1 ( 5GA1 )
· wiring from the EIU-1 (1KS1) to the LGCIU-1 (5GA1)
· EIU-1 ( 1KS1 )
2 Job Set-up Information
A. Referenced Information
REFERENCE DESIGNATION
Ref. AMM 24-41-00-861-002 Energize the Aircraft Electrical Circuits from the External Power
Ref. AMM 24-41-00-862-002 De-energize the Aircraft Electrical Circuits Supplied from the External
Power
Ref. AMM 31-60-00-860-001 EIS Start Procedure
Ref. AMM 31-60-00-860-002 EIS Stop Procedure
Ref. AMM 32-31-71-000-001 Removal of the LGCIU
Ref. AMM 32-31-71-400-001 Installation of the LGCIU
Ref. AMM 32-31-73-000-001 Removal of the MLG Proximity-Sensors
Ref. AMM 32-31-73-400-001 Installation of the MLG Proximity-Sensors
Ref. AMM 71-13-00-010-010 Opening of the Fan Cowls 437AL(447AL),438AR(448AR)
Ref. AMM 71-13-00-410-010 Closing of the Fan Cowls 437AL(447AL),438AR(448AR)
Ref. ASM 73-25-16
Ref. AMM 73-25-34-000-041 Removal of the Engine Interface Unit (EIU)
Ref. AMM 73-25-34-400-041 Installation of the Engine Interface Unit (EIU)
Engine Interface Unit - Harness Trouble Shooting on Engine 1 SHEET 1
Figure 73(IAE)-25-00-991-00300-A / SHEET 1/1 - Engine Interface Unit - Harness Trouble Shooting on
Engine 1 not printed, as per printing preferences
3. Fault Confirmation
Subtask 73-25-00-860-058-A
A. Job Set-up
(1) Energize the aircraft electrical circuits Ref. AMM 24-41-00-861-002 .
(2) On the panel 50VU, push the ENG/FADEC GND PWR/1 pushbutton switch.
(3) Do the EIS start procedure (Upper ECAM DU and lower ECAM DU only)
Ref. AMM 31-60-00-860-001 .
Subtask 73-25-00-710-284-A
B. Test
(1) Not applicable. Fault is set in flight.
4. Fault Isolation
Subtask 73-25-00-810-170-A
A. If the fault symptom is identified by the maintenance message EIU/LGCIU/WOW1:
· replace the PROX SNSR-R L/G EXT, SYS 1 ( 20GA ) Ref. AMM 32-31-73-000-001 and Ref.
AMM 32-31-73-400-001 .
(1) If the fault continues:
· replace the PROX SNSR-L L/G EXT, SYS 1 ( 21GA ) Ref. AMM 32-31-73-000-001 and Ref.
AMM 32-31-73-400-001 .
(2) If the fault continues:
· replace the LGCIU-1 ( 5GA1 ) Ref. AMM 32-31-71-000-001 and Ref. AMM 32-31-71-400-001
(3) If the fault continues:
· do a check of the wiring from the EIU-1 (1KS1) to the LGCIU-1 (5GA1) pins AA/5D, 5E to pins
AB/3G, 3K. Ref. ASM 73-25-16
(4) If the fault continues:
· replace the EIU-1 ( 1KS1 ) Ref. AMM 73-25-34-000-041 and Ref. AMM 73-25-34-400-041 .
(5) If the fault continues:
· open the fan cowl doors 437AL and 438AR Ref. AMM 71-13-00-010-010
· do a check and repair as necessary, the wiring from the EEC connector 4000KS-J1 pins P, N to the
harness connector 402VC-A pins 4, 12.
(Ref. Fig. Engine Interface Unit - Harness Trouble Shooting on Engine 1 SHEET 1)
(6) If the fault continues:
· do a check and repair as necessary, the wiring from the EEC connector 4000KS-J7 pins P, N to the
harness connector 402VC-A pins 4, 12.
(Ref. Fig. Engine Interface Unit - Harness Trouble Shooting on Engine 1 SHEET 1)
Subtask 73-25-00-710-285-A
B. After the subsequent flight, make sure that the fault does not continue.
5. Close-up
Subtask 73-25-00-860-059-A
A. Put the aircraft back to its initial configuration.
(1) Do the EIS stop procedure
Ref. AMM 31-60-00-860-002 .
(2) On the panel 50VU, push the ENG/FADEC GND PWR/1 pushbutton switch.
(3) De-energize the aircraft electrical circuits Ref. AMM 24-41-00-862-002 .
(4) Make sure that the fan cowls doors 437AL and 438AR are closed Ref. AMM 71-13-00-410-010 . [Rev.6 from Feb 2017] 2026.04.04 04:36:24 UTC