Failure of the GLC 1 Status Indication

TASK 24-22-00-810-825-A
Failure of the GLC 1 Status Indication

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 242202
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 24-22-55-000-001	Removal of the Contactors
AMM 24-22-55-400-002	Installation of the Contactors
AMM 24-41-00-740-002	Operational Check of the GAPCU via the CFDS

3. Fault Confirmation
Subtask 24-22-00-740-061-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the BITE test of the GAPCU AMM 24-41-00-740-002.
(a) If the BITE test gives the message TEST FAILED:

(b) If the BITE test gives the message TEST PASSED:

4. Fault Isolation
Subtask 24-22-00-810-088-A ** ON A/C NOT FOR ALL

A. If the BITE test gives the message TEST FAILED:

(1) If the maintenance message GCU1 (1XU1) comes into view:

Subtask 24-22-00-810-077-A ** ON A/C NOT FOR ALL

B. If the BITE test gives the message TEST PASSED:

do a check of the contact for correct operation of the GLC 1 (9XU1) between pins B/18 and B/20 of the GLC 1 ASM 242202.

(1) If the contact does not operate correctly:

(2) If the contact operates correctly:

do a check of the wiring of the GLC 1 sense circuit ASM 242202 for an open circuit between:
. pin 2 of the ELEC/GCU1 circuit breaker (2XU1) and pin A/B of the function relay (20XU)
. pin A/3 of the function relay and pin B/18 of the GLC 1 (9XU1)
. pin B/20 of the GLC 1 and pin A/29 of the diode module 2420VD
. pin A/14 of the diode module 2420VD and pin A/6A of the GCU 1.

(a) If the wiring is not correct:

(b) If the wiring is correct:

Subtask 24-22-00-740-062-A ** ON A/C NOT FOR ALL

C. When you replace a component or repair the wiring:

do the subsequent flight before you do the check of the Class 3 Faults of the GAPCU from the CFDS to make sure that the system operates correctly.
If the test continues to give the fault message, continue the trouble shooting procedure.

[Rev.8 from Aug 2018] 2026.04.04 04:26:38 UTC