02/24/21
Message Overview:
Message Description:
L-RIU bus data not received at L-IOC and 3-of (L-VHF, L-PFD, L-MFD, L-CDU, DCU, L-NAV, L-DME, TSS).
Possible Causes:
- Left Radio Interface Unit (RIU 1) (A17)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Radio Interface Unit (RIU) | AMM 23-51-21-000-801 |
| Installation of the Radio Interface Unit (RIU) | AMM 23-51-21-400-801 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Wire Repair | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Reset RIU 1A (CB1-B5) and RIU 1B/AURAL (CB1-B4) circuit breaker.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Confirm the presence of the 28 VDC and the ground at the left RIU connectors A17P1 and A17P2. Repair/replace as required.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Replace the left RIU.
- Do close out.