Message Name:

N2 MONOPOLE 1B

Message Code:

B3-303590

Associated CAS:

L ENGINE MINOR FAULT
(Advisory)

Left engine N2 monopole fault 1B.

[MCID 0302]
N2 Monopole 1B.
Detection of a fault in the N2 monopole harness between the N2 monopole and the ECU B. The ECU B cannot support full system operation.

• Permanent Magnet Alternator (PMA)
• N2 Monopole
• Wiring Harness (W6)
• Wiring Harness (W3)
• Full Authority Digital Engine Control (FADEC) Electronic Control Unit B (ECU) (A43)

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. If the 'L' or 'R ENGINE MINOR FAULT' advisory CAS message is shown with this fault, this is a Short Term dispatch (STD) fault and is subject to correction outlined in the Honeywell LEMM SUBTASK 5-10-00-200-003.
2. If a L or R FADEC FAIL CAS message is shown, this is a No Dispatch (ND) fault and is subject to correction outlined in the Honeywell LEMM SUBTASK 5-10-00-200-003.
3. Check for the following MDC messages displayed with the fault: X-channel bus 1A (MCID 0905), X-channel bus 1B (MCID 0906), X-channel discrete 1A (MCID 0933), X-channel discrete 1B (MCID 0934). If any of the above MCID codes are posted, correct the cross channel faults first.
4. If MDC message (MCID 0902) PMA FAULT 4, (MCID 0903) PMA FAULT 1A or (MCID 0904) PMA FAULT 1B is shown, correct those fault(s) first.

1. MCID 0302 fault only is present, troubleshoot using the following steps for aircraft and engine fault isolation with reference to the Light Engine Maintenance Manual TASK 72-00-00-810-044.
2. Reset and reboot the ECU to recheck the MDC MCID for the posted fault.
3. Remove the connector on the ECU 1A W6P2, inspect for burned or pushed back pins/sockets, then check the following segments per the table, repair wiring if required per the wiring manual standard practices.

   From	To	Value
   W3P9 Pin 18	W3P9 Pin 17	50 to 550 Ω

4. If the resistance values check good, proceed to step 7, if the resistance values were bad at the ECU, perform a resistance check on the N2 monopole as shown in the table below

   From	To	Value
   W3P6 Pin 3	W3P6 Pin 4	50 to 550 Ω

5. If the resistance values fail at the N2 sensor, replace the sensor IAW Honeywell LEMM TASK 77-10-05-050-801. If the resistance values check good, suspect the W3 or W6 wiring harness, isolate wiring and replace defective harness per the Honeywell LEMM TASK 76-10-01-050-801.
6. If the wiring and monopole check good, consider swapping or replacing the A channel ECUs for the left engine, remove and replace IAW AMM TASK 76-10-05-000-801, TASK 76-10-05-400-801 then recheck the system for the fault.