Fault Message:

GCU4 [GEN CURRENT LIMIT INHIB]

Fault Code:

2424232LPS

Associated CAS:

GEN 4 FAIL
(Advisory)

The Generator Control Unit (GCU) 4 detects the current limit inhibit discrete for 5 Sec without the logic signal ±15 V supply.

• Generator Control Unit (GCU) 4 (A59)
• AC Power Center (ACPC) (A54)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

A GCU patch cable (GSE REF # 24X-24-02) can be used to swap GCUs 1, 4 and 5 into position 2 or 3 (for troubleshooting only).

The GCU NVMs can only be downloaded at position #2 or #3.

1. Perform a continuity check between GCU 4 and ground as follows:

   From	To	Result
   A59P2-46	Ground

   1. If there is no continuity, go to step 3.
   2. If there is continuity, continue with next step.

2. Swap the GCU 4 with GCU 3 (physically or using the GCU patch cable).

   1. If system checks are good, replace GCU 4 and do close out.
   2. If fault remains, continue with next step.

3. Remove all 3 PLCs inside the ACPC.
4. Perfom a continuity check between ACPC and ground as follows:

   From	To	Result
   A54P2-n	Ground

   1. If there is continuity, go to step 6.
   2. If there is no continuity, continue with next step.

5. Perform a wiring check (shorted to ground= failure) between ACPC and GCU 4 as follows:

   From	To	Result
   A54P2-n	A59P2-46

   1. If wiring checks are not good, repair defective wiring as required and do close out.
   2. If wiring checks are good, continue with next step.

6. Replace ACPC.
7. Do close out.