Failure of the RS422 Electrical Connection between the GPCU and the GCU 1

TASK 24-41-00-810-806-A
Failure of the RS422 Electrical Connection between the GPCU and the GCU 1

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 24-22-34-000-001	Removal of the GCU-1(2)
AMM 24-22-34-400-001	Installation of the GCU-1(2)
AMM 24-41-00-740-004	Operational Check of the GPCU via the CFDS
ASM 244102
AMM 24-41-34-000-001	Removal of the Ground Power Control Unit (GPCU)
AMM 24-41-34-400-001	Installation of the Ground Power Control Unit (GPCU)

3. Fault Confirmation
Subtask 24-41-00-710-059-A ** ON A/C NOT FOR ALL

A. Test
Do the operational check of the GPCU with the CFDS AMM 24-41-00-740-004.

4. Fault Isolation
Subtask 24-41-00-810-055-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message CHECK SERIAL LINK GPCU TO GCU 1:

do a check of the wiring for short to ground or open circuit between respectively the GPCU pins A/13C, A/14C and the GCU 1 pins B/14C, B/14D ASM 244102.

(1) If the wiring is not correct:

(2) If the wiring is correct:

(3) If the fault continues:

Subtask 24-41-00-710-060-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:26:53 UTC