W DOC AIRBUS | TSM A320F

Failure of the Interlock Circuit (External Power / GAPCU)

TASK 24-41-00-810-811-A
Failure of the Interlock Circuit (External Power / GAPCU)

1. Possible Causes
  • external power source
  • wiring
  • GAPCU [24XG]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 24-41-00-861-002
Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002
De-energize the Aircraft Electrical Circuits Supplied from the External Power
ASM 244101
AMM 24-41-34-000-001
Removal of the Ground Power Control Unit (GPCU)
AMM 24-41-34-400-001
Installation of the Ground Power Control Unit (GPCU)
3. Fault Confirmation
Subtask 24-41-00-860-057-A ** ON A/C NOT FOR ALL
A. Test
Not applicable.
Subtask 24-41-00-860-074-A ** ON A/C NOT FOR ALL
B. Aircraft Maintenance Configuration
   (1) Energize the aircraft electrical circuits from the external power AMM 24-41-00-861-002.
4. Fault Isolation
Subtask 24-41-00-810-071-B ** ON A/C NOT FOR ALL
A. If the fault symptom is identified by the CFDS messages EXT PWR INTLK/ GAPCU (24XG) or EXTERNAL POWER INTERLOCK/ GAPCU (24XG):
   (1) Do a check for 28VDC between pin E and pin F of the external power receptacle (20XG) ASM 244101.
     (a) If there is no 28VDC:
  • De-energize the aircraft electrical circuits from the external power AMM 24-41-00-862-002.
  • Replace the external power source .
     (b) If there is 28VDC:
  • De-energize the aircraft electrical circuits from the external power AMM 24-41-00-862-002.
  • Do a check of the wiring between ASM 244101:
    . Pin E of the external power receptacle (20XG) and pin B/11E of the GAPCU (24XG)
    . Pin F of the external power receptacle (20XG) and pin B/12E of the GAPCU (24XG).
       1 If the wiring is not correct:
  • Repair it.
       2 If the wiring is correct:
Subtask 24-41-00-860-058-A ** ON A/C NOT FOR ALL
B. Do this procedure to make sure that the system operates correctly.
   (1) Energize the aircraft electrical circuits from the external power AMM 24-41-00-861-002.
   (2) De-energize the aircraft electrical circuits from the external power AMM 24-41-00-862-002.
[Rev.8 from Aug 2018] 2026.04.04 04:26:53 UTC
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