W DOC AIRBUS | TSM A320F

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

TASK 73-25-00-810-920-A
Loss of 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]
  • C/B-ENGINE/ENG1/FADEC B/AND EIU 1 [4KS1]
  • harnesses J1 and J2
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 73-25-00-710-288-A ** ON A/C NOT FOR ALL
A. Do the operational test of the FADEC 1A on the ground (with engine motoring) AMM 73-29-00-710-040.
4. Fault Isolation
Subtask 73-25-00-865-060-A ** ON A/C NOT FOR ALL
A. Table of the circuit breakers used in this procedure:
PANELDESIGNATIONFINLOCATION
** ON A/C NOT FOR ALL
49VUENGINE/1/FADEC A/AND EIU 12KS1A04
121VUENGINE/ENG1/FADEC B/AND EIU 14KS1R41
Subtask 73-25-00-810-172-A ** ON A/C NOT FOR ALL
B. If the test gives the maintenance message EIU, ECU (CR3 DIODE):
  • disconnect the connectors J1 and J2 from the ECU (4000KS) and do a check for 28VDC at pins J1/13 and J2/13 with the FADEC GND PWR pushbutton switch released (the ON legend is on) ASM 732505.
   (1) If there is 28VDC:
   (2) If there is no 28VDC:
  • do a check for 28VDC at EIU 1 (1KS1) pins AC/9, 11 ASM 732505.
     (a) If there is no 28VDC:
  • do a check for open or short to ground at the aircraft wiring from the circuit breakers (2KS1) and (4KS1) to EIU 1 (1KS1) pins AC/9, 11.
       1 If there is a short to ground:
  • repair the above wiring.
       2 If there is no short to ground:
  • replace the defective C/B-ENGINE/1/FADEC A/AND EIU 1 [2KS1] or C/B-ENGINE/ENG1/FADEC B/AND EIU 1 [4KS1] .
     (b) If there is 28VDC:
  • do a check for open or short to ground at the harnesses J1 and J2 between the EIU 1 (1KS1) and the ECU (4000KS), pins AC/2, 7 to pins J1/13, J2/13. Replace the harness J1 or J2 if necessary ASM 732505.
     (c) If the fault continues:
  • make sure that there is no ground signal at EIU 1 (1KS1) pin AA/5B ASM 732508.
     (d) If the fault continues:
Subtask 73-25-00-710-289-A ** ON A/C NOT FOR ALL
C. Do the test given in Para. 3.A.
[Rev.8 from Aug 2018] 2026.04.04 04:35:48 UTC
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