Loss of Data on the Second and Primary ECS Buses to the EIU 1

TASK 73-25-00-810-873-A
Loss of Data on the Second and Primary ECS Buses to the EIU 1

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 21-61-34-000-002	Removal of the Air-Conditioning System Controller
AMM 21-61-34-400-002	Installation of the Air-Conditioning System Controller
AWM 732519
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)

3. Fault Confirmation
Subtask 73-25-00-710-206-A ** ON A/C NOT FOR ALL

A. Test
(1) Not applicable.

Subtask 73-25-00-710-206-B ** ON A/C NOT FOR ALL

A. Test
(1) Not applicable.

4. Fault Isolation
Subtask 73-25-00-810-128-C ** ON A/C NOT FOR ALL

A. If the fault is also present on engine 1:

replace the CONT-AIR COND SYSTEM 1 [47HH] and CONT-AIR COND SYSTEM 2 [57HH] AMM 21-61-34-000-002 and AMM 21-61-34-400-002.

(1) If the fault is present on engine 1 only:

do a check of the wiring between the EIU1 (1KS1) pins AA/2J, AA/2K and terminal block 1853VT and between the EIU1 (1KS1) pins AA/3J, AA/3K and terminal block 1862VT AWM 732519.

(a) If the wiring is not correct:

(b) If the wiring is correct:

Subtask 73-25-00-710-207-A ** ON A/C NOT FOR ALL

B. No additional maintenance action is required if the fault is not confirmed.
(1) Repeat the fault isolation procedure if the fault continues.

[Rev.8 from Aug 2018] 2026.04.04 04:35:45 UTC