Loss of the ECU Cross Channel on Engine 1

TASK 77-10-00-810-809-A
Loss of the ECU Cross Channel on Engine 1

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-30-000-002	Removal of the Control Alternator
AMM 73-21-30-400-002	Installation of the Control Alternator
AMM 73-21-50-000-008	Removal of the J9 Harness
AMM 73-21-50-400-008	Installation of the J9 Harness
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 732518

3. Fault Confirmation
Subtask 77-10-00-710-066-A ** ON A/C NOT FOR ALL

A. Not apllicable

4. Fault Isolation
Subtask 77-10-00-810-058-A ** ON A/C NOT FOR ALL

A. If the fault symptom is identified by the maintenance message ALT, ECU, J9:

NOTE 1 : In the usual operating condition, a fault of the harness J9

is detected with the test of the channel A.

NOTE 2 : When a cross channel fault occurs, the harness fault is

detected during the test on the opposite channel.

NOTE 3 : For the trouble shooting, do the procedure for the plug which is

shown on the fault message and not the channel which is given at the

end of the post flight report.

do a check for open or short to ground of the harness J9 between the ECU (4000KS) and the control alternator pins J9/4, 5, 13, 14, 15 to pins J9/2, 3, 4, 5 ASM 732518.

(1) If the wiring is not correct:

(2) If the wiring is correct:

(a) If the resistance values are in the specified limits:

(b) If the resistance values are out of the specified limits:

disconnect the harness J9 from the control alternator and do a check of the alternator resistance between:
. pins 2 and 5 (< 1 Ohm)
. pins 3 and 5 (< 1 Ohm)
. pins 4 and 5 (< 1 Ohm)
. pin 5 and the ground (> 10 Megohms).

1 If the resistance values are in the specified limits:

2 If the resistance values are out of the specified limits:

[Rev.8 from Aug 2018] 2026.04.04 04:37:36 UTC