Failure of the Generator Control Unit 1

TASK 24-20-00-810-870-A
Failure of the Generator Control Unit 1

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 24-41-00-740-002	Operational Check of the GAPCU via the CFDS

3. Fault Confirmation
Subtask 24-20-00-740-058-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 24-20-00-810-127-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:

(2) If the fault continues:

do a check and repair the wiring between the GCU 1 and the GLC 1 auxiliary control relay (4XU1) ASM 242202 for a short to 28VDC between:
. pin B/10J of the GCU 1 and pin A/C3 of the ELEC/GEN 1 pushbutton switch (3XU1)
. pin A/C1 of the ELEC/GEN 1 pushbutton switch and pin A/A of the function relay (20XU)
. pin A/1 of the function relay and pin A/X1 of the GLC 1 auxiliary control relay.

Subtask 24-20-00-740-059-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:26:16 UTC