04/09/21
Message Overview:
Message Description:
Left engine TT2 sensor/heater fault 1B.
[MCID 0802]
TT2 Sensor/Heater Fault 1B.
Detection of a fault in the TT2 sensor/heater wiring harness, between the TT2 sensor/heater and the ECU B. The ECU B cannot support full system operation.
Possible Causes:
- Wiring Harness open from the TT2 Sensor to the ECU B
- TT2 Sensor
- Full Authority Digital Engine Control Unit (FADEC) Electronic Control Unit B (ECU) (A43)
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
- If the cyan 'L or R ENG 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.
- 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.
- 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.
Quick Links:
| Operational Test of the Nacelle Anti-Ice System | AMM 30-21-00-710-801 |
| General Visual Inspection of the Engine Wiring Harness | AMM 71-50-00-210-802 |
| Removal of the FADEC Electrical Harness from the Left Engine | AMM 71-50-05-000-802 |
| Installation of the FADEC Electrical Harness on the Left Engine | AMM 71-50-05-400-802 |
| Removal of the Engine Electronic Control Unit (ECU) | AMM 76-10-05-000-801 |
| Installation of the Engine Electronic Control Unit (ECU) | AMM 76-10-05-400-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
| Electrical Connectors - Maintenance Practice - ALL | SPM 20-20-00-02 |
Troubleshooting Recommendations:
- MCID 802 fault only is present, troubleshoot using the following steps for aircraft and engine fault isolation with reference to the Light Engine Maintenance Manual TASK 72-00-00-810-110.
- Possible Causes:
- TT2 sensor
- Wiring Harness (LH Engine) between TTs sensor to ECU A
- ECU B
- Check & verify the system operation IAW AMM, look for the system fault by viewing the Ice synoptic page looking for the amber T2 fault and verify current faults in the MDC and see if B3-304644 has posted again. If the fault still exists, continue, otherwise closeout.
- If MCID is listing both 801 ECU A fault, and 802 ECU B faults refer to Operator Information Wire AS900-2006-OIW-14. Replace the TT2 connector IAW the LEMM.
- Gain access to the following connectors, inspect for damage, then check the following segments per the table, repair wiring if required per the 20-10-02 wiring manual standard practices
From To Value Pin 3 Pin 5 50 to 150 Ω W6P7 Pin 3 W6P7 Pin 4 50 to 150 Ω - If no discrepancy is noted, suspect the Electronic Control Unit, remove and replace IAW AMM.
