Message Name:

NO A-DCU-2 BUS OUTPUT

Message Code:

B3-006490

Associated CAS:

None

No A-DCU-2 data received by at least 2-of (MFD1, MFD2, PFD1, PFD2).

• Data Concentrator Unit (DCU) (A14)
• Left Primary Flight Display (PFD 1) (A27)
• Right Primary Flight Display (PFD 2) (A26)
• Left Multi-Function Display (MFD 1) (A29)
• Right Multi-Function Display (MFD 2) (A28)
• Junction Box 2 (JB2)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Reset the following Circuit Breakers. Is the fault message still present?

   NAME	LOCATION & NUMBER
   EICAS DCU A	CB1-D1
   L PFD	CB1-C3
   R PFD	CB2-C3
   L MFD	CB1-C5
   R MFD	CB2-C5

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

2. Remove one Adaptive Flight-Display Unit at the time (3 must be connected). Is the fault message is still present?

1. If NO, replace the defective Adaptive Flight-Display Unit.
2. If YES, repeat this step until all 4 Adaptive Flight-Display Units are confirmed not causing the fault message, then, continue with next step.

3. Do wiring check between DCU (A14) and the 4 Adaptive Flight-Display Units, through Junction Box 2, for the following wires:

   From	To	Result
   Conn. A14FP1 - 3A	Conn. A26P1 - 59
   Conn. A14FP1 - 3B	Conn. A26P1 - 69
   Conn. A14FP1 - 3A	Conn. A28P1 - 59
   Conn. A14FP1 - 3B	Conn. A28P1 - 69
   Conn. A14FP1 - 3A	Conn. A29P1 - 59
   Conn. A14FP1 - 3B	Conn. A29P1 - 69
   Conn. A14FP1 - 3A	Conn. A27P1 - 59
   Conn. A14FP1 - 3B	Conn. A27P1 - 69

   1. If the check is satisfactory, continue with next step.
   2. If the check is not satisfactory, repair defective wire or replace JB2.

4. Replace DCU (A14).
5. Do close out.