03/22/21
Message Overview:
Message Description:
Input from IRS1 to IOC 1X is inactive, and at least 3 of the following; L-IRS-1 input to FGC1 is inactive, L-IRS-2 input to MFD1 is inactive, L-IRS-2 input to PFD1 is inactive & L-IRS-1 to SPC is inactive.
Possible Causes:
- Internal Reference Unit (IRU) No. 1 (A233)
- Junction Box 1 (JB1)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Junction Box JB2 Circuit-Cards | AMM 24-63-05-000-802 |
| Installation of the Junction Box JB2 Circuit-Cards | AMM 24-63-05-400-802 |
| Removal of the Inertial Reference Unit (IRU) | AMM 31-45-01-000-801 |
| Installation of the Inertial Reference Unit (IRU) | AMM 31-45-01-400-801 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Repair Wiring | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Reset IRU 1 (CB1-C2) circuit breaker.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Confirm 28 VDC and ground returns are available at IRU 1 connector A233P1. Repair/replace as required.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Swap IRUs.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Replace Junction Box 1.
- Do close out.