Loss of the ACS1 Signal of the ELAC1 MON Side and SEC1 MON Side

TASK 27-90-00-810-820-A
Loss of the ACS1 Signal of the ELAC1 MON Side and SEC1 MON Side

1. Possible Causes

ELAC-1 [2CE1]
SEC-1 [1CE1]
wiring of the ACS1 SPLY XDCR signal from the SEC1 MON side to the COM side
wiring of the ACS1 SPLY XDCR COM signal from the SEC1 MON side to the second terminal block

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 27-90-00-810-801-A	Failure of an Alternating Current Supply (ACS)
AMM 27-93-34-000-001	Removal of the ELAC
AMM 27-93-34-400-001	Installation of the ELAC
ASM 279407
AMM 27-94-34-000-001	Removal of the SEC
AMM 27-94-34-400-001	Installation of the SEC
AMM 27-96-00-740-001	BITE Test of the EFCS (Ground Scanning)

3. Fault Confirmation
Subtask 27-90-00-740-087-A

A. Test
(1) Do the BITE test of the EFCS (ground scanning) AMM 27-96-00-740-001.

4. Fault Isolation
Subtask 27-90-00-810-069-A

A. If the ground scanning gives at least two maintenance messages of the list below:
L ELEV POS MON XDCR OF ELAC1/SEC1
L G ELEV MODE XDCR 34CE1
R B ELEV POS MON XDCR OF ELAC1/SEC1
R Y ELEV MODE XDCR 34CE2
THS ACTR XDCR2 MON 9CE
(1) Remove the ELAC1 AMM 27-93-34-000-001 and the SEC1 AMM 27-94-34-000-001.
(2) At the SEC1 receptacle, do a check of the resistance between the pin AB/9E and the pin AB/9F ASM 279407:
(a) If the resistance is less than 10 Ohms:
1 Do this procedure (Ref. TSM TASK 27-90-00-810-801).
2 Replace the ELAC-1 [2CE1] AMM 27-93-34-000-001 and AMM 27-93-34-400-001.
3 Replace the SEC-1 [1CE1] AMM 27-94-34-000-001 and AMM 27-94-34-400-001.
(b) If the resistance is more than 10 Ohms:
1 Replace the SEC-1 [1CE1] AMM 27-94-34-000-001 and AMM 27-94-34-400-001.
Install the ELAC1 AMM 27-93-34-400-001.
2 If the fault continues:

replace the ELAC-1 [2CE1] AMM 27-93-34-000-001 and AMM 27-93-34-400-001.

3 If the fault continues:
a Do a check of the wiring of the ACS1 SPLY XDCR signal from the SEC1 MON side to the COM side , pins AE/10D and AE/10E to pins AB/8F and AB/8E ASM 279407.

if the wiring is correct, continue the trouble shooting
if the wiring is not correct, repair the above wiring.

b Do a check of the wiring of the ACS1 SPLY XDCR COM signal from the SEC1 MON side to the second terminal block , pins AB/9E and AB/9F ASM 279407.

if the wiring is correct, continue the trouble shooting
if the wiring is not correct, repair the above wiring.

c Do the failure of an alternating current supply (ACS) procedure (Ref. TSM TASK 27-90-00-810-801).

Subtask 27-90-00-740-088-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:27:53 UTC