Overcurrent of the GEN 1 Because of a Failure of the BTC 1 Control Circuit

TASK 24-20-00-810-860-A
Overcurrent of the GEN 1 Because of a Failure of the BTC 1 Control Circuit

1. Possible Causes

GCU-1 [1XU1]
wiring
BTC-1 [11XU1]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 24-20-00-810-888-A	Failure of an Opposite Channel of the Generator 1 Channel
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 24-20-00-740-062-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:

do the trouble shooting given in Para 4.A.

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

do the trouble shooting given in Para 4.B.

4. Fault Isolation
Subtask 24-20-00-810-133-A ** ON A/C NOT FOR ALL

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

push the line key adjacent to the TEST FAILED message.

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

replace the GCU-1 [1XU1] AMM 24-22-34-000-001 and AMM 24-22-34-400-001.

Subtask 24-20-00-810-200-A ** ON A/C NOT FOR ALL

B. If the BITE test gives the message TEST PASSED:
(1) Do the trouble shooting for a delta current condition of the IDG 1 (Ref. TSM TASK 24-20-00-810-888).
(2) If the fault continues:

do a check of the coil return wiring for a short circuit or a short to ground between pin B/5 of the BTC 1 and pin A/9A of the GCU 1 ASM 242202.

(a) If the wiring is not correct:

repair or replace as necessary.

(b) If the wiring is correct:

do a check of the auxiliary contact for correct operation between pin B/29 and pin B/27 of the BTC 1 ASM 242202.

1 If there is no continuity:

replace the BTC-1 [11XU1] AMM 24-22-55-000-001 and AMM 24-22-55-400-002.

2 If there is continuity:

do a check of the wiring for an open circuit condition between pin B/29 of the BTC 1 and pin A/4C of the GCU 1 ASM 242202.

a If the wiring is not correct:

repair or replace as necessary.

b If the wiring is correct:

replace the GCU-1 [1XU1] AMM 24-22-34-000-001 and AMM 24-22-34-400-001.

Subtask 24-20-00-740-096-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:26:15 UTC