Message Name:

GCU3 GLC STATUS/SENSING FAULT

Message Code:

2423231LPS

Associated CAS:

None

Generator Control Unit (GCU) 3 has detected a Generator Line Contactor status/status sensing circuit fault, consequently resulting in the Generator 3 tripped off-line or not come on-line.

• Generator Control Unit (GCU) 3 (A58)
• Generator Line Contactor (GLC) 3 (K10)
• 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 GCU 1, GCU 2, GCU 3, GCU 4 and the APU GCU into a different position (for troubleshooting only). You can monitor the GCU faults in the CAIMS via the fault messages page.

1. Interchange GCU 3 with GCU 2 (physically or using the GCU patch cable). Is the fault still present?

   1. If YES, continue with next step.
   2. If NO, replace GCU 3 and do close out.

2. Disconnect GCU 3 connector A58P2. Access ACPC Primary logic assembly and disconnect GLC 3 (K10) connector P303. Perform a continuity check as follows:

   From	To	Result
   A58P2-19	Ground

   1. If there is continuity, repair defective wiring as required or replace ACPC if the defect is inside the ACPC and do close out.
   2. If there is no continuity, continue with next step.

3. Perform a continuity check as follows:

   From	To	Result
   A58P2-19	P303-8

   1. If there is continuity, continue with next step.
   2. If there is no continuity, repair defective wiring as required or replace ACPC if the defect is inside the ACPC and do close out.

4. Perform a continuity check as follows:

   From	To	Result
   P303-22	Ground

   1. If there is no continuity, continue with next step.
   2. If there is continuity, check connections on TB201-3 and TB601-1 and repair as required and do close out.

5. Interchange GLC 3 (K10) with GLC 4 (K13). Is the fault still present?

   1. If YES, continue with next step.
   2. If NO, replace GLC 3 (K10) and do close out.

6. Replace ACPC.
7. Do close out.