Message Name:

NOT DISENGAGED

Message Code:

B3-006344

Associated CAS:

APU STARTER FAIL ON
(Caution)

Auxiliary Power Unit (APU) Electronic Control Unit (ECU) is reporting the start contractor did not disengage.

• Auxiliary Power Start Contractor (APSTC) (K62)
• Auxiliary Power Unit (APU) Electronic Control Unit (ECU) (A39)
• Auxiliary Power Center Primary-Logic (PCB11)
• Auxiliary DC Power Center (ADCPC) (A196)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTE 1: The APU Master Switch must be selected at RUN (or START) to provide the primary power to the APU ECU.

1. Do wiring check from the Auxiliary DC Power Center (A196) to APU ECU (A39) for the following wire:

   From	To	Result
   Conn. A196P1-Y	Conn. A39BP1-1B

   1. If the check is satisfactory, continue with next step.
   2. If the check is not satisfactory, repair defective wiring.

2. Disconnect the Auxiliary Power Center Start Contactor (K62) connector. Do visual inspection of the connectors and associated wiring for any loose pins and/or damaged wire.

   1. If inspection is satisfactory, continue with next step.
   2. If inspection is not satisfactory, go to step 6.

3. Verify Auxiliary Power Center Start Contactor (K62) main contacts by measuring the resistances at the contactor connector (J-side) as per the following table:

   Measurement at	Expected Results	Results
   Main contact #1 and Main contact #2	Open

   1. If the verification is satisfactory, continue with next step.
   2. If the verification is not satisfactory, replace the defective Auxiliary Power Center Start Contactor (K62).

4. Replace APU ECU (A39). Is the fault message still present?

   1. If YES, continue with next step.
   2. If NO, do close out.

5. Replace Auxiliary Power Center Primary-Logic (PCB11). Is the fault message still present?

   1. If YES, continue with next step.
   2. If NO, do close out.

6. Replace Auxiliary DC Power Center (A196).
7. Do close out.