W DOC AIRBUS | TSM A320F

Loss of the 28VDC Power Supply of the ECU on the Engine 1

TASK 73-25-00-810-909-A
Loss of the 28VDC Power Supply of the ECU on the Engine 1

1. Possible Causes
  • EIU-1 [1KS1]
  • ECU [4000KS]
  • aircraft wiring
  • C/B-ENGINE/1/FADEC A/AND EIU 1 [2KS1]
  • harness J1
  • harness J1
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
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 732505
ASM 732508
AMM 73-25-34-000-040
Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-400-040
Installation of the Engine Interface Unit (EIU)
AMM 73-29-00-710-040
Operational Test of the FADEC on the ground (with Engine Motoring)
3. Fault Confirmation
Subtask 73-25-00-865-052-A ** ON A/C NOT FOR ALL
A. Make sure that this(these) circuit breaker(s) is(are) closed:
PANELDESIGNATIONFINLOCATION
** ON A/C NOT FOR ALL
49VUENGINE/1/FADEC A/AND EIU 12KS1A04
Subtask 73-25-00-710-268-A ** ON A/C NOT FOR ALL
B. Test
   (1) If the circuit breaker (2KS1) is open, refer to Para. 4.A.(2).
   (2) Do the operational test of the FADEC 1A on the ground (with engine motoring) AMM 73-29-00-710-040.
4. Fault Isolation
Subtask 73-25-00-810-160-A ** ON A/C NOT FOR ALL
A. If the test gives the maintenance message EIU - 28V, ECU:
  • do a check of the status of the circuit breaker (2KS1).
   (1) If the circuit breaker is closed:
  • disconnect the connector J1 from the ECU (4000KS) and do a check for 28VDC at pins J1/13 with the FADEC GND PWR pushbutton switch released (the ON legend is on) ASM 732505.
     (a) If there is 28VDC:
     (b) If there is no 28VDC:
  • do a check for 28VDC at EIU 1 (1KS1) pin AC/11 ASM 732505.
       1 If there is no 28VDC:
  • do a check for open or short to ground at the aircraft wiring from the circuit breaker (2KS1) to EIU 1 (1KS1) pin AC/11.
         a If there is a short to ground:
  • repair the above wiring.
         b If there is no short to ground:
  • replace the C/B-ENGINE/1/FADEC A/AND EIU 1 [2KS1] .
       2 If there is 28VDC:
  • do a check for open or short to ground at the harness J1 between the EIU 1 (1KS1) and the ECU (4000KS), pin AC/7 to pin J1/13. Replace the harness J1 if necessary ASM 732505.
       3 If the fault continues:
  • make sure that there is no ground signal at EIU 1 (1KS1) pin AA/5B ASM 732508.
     (c) If the fault continues:
   (2) If the circuit breaker (2KS1) is open:
  • close the circuit breaker.
     (a) If the circuit breaker trips:
     (b) If the fault continues:
  • do a check for a short to ground at the harness J1 between the EIU 1 (1KS1) and the ECU (4000KS), pin AC/7 to pin J1/13.
       1 If there is a short to ground:
  • replace the harness J1 .
       2 If there is no short to ground:
  • do a check for a short to ground at the aircraft wiring between EIU 1 (1KS1) pins AC/11 and the circuit breaker (2KS1).
         a If there is a short to ground:
  • repair the above wiring.
         b If there is no short to ground:
  • replace the C/B-ENGINE/1/FADEC A/AND EIU 1 [2KS1] .
Subtask 73-25-00-710-269-A ** ON A/C NOT FOR ALL
B. Do the test given in Para. 3.B.
[Rev.8 from Aug 2018] 2026.04.04 04:35:48 UTC
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