05/27/22
Message Overview:
Message Description:
Proximity Sensor Electronic Unit detects low power from 28 VDC Left ESS Bus, aircraft power interface requires troubleshooting.
Possible Causes:
- Proximity-Sensor Electronic Unit (PSEU) (A9)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Proximity-Sensor Electronic Unit (PSEU) | AMM 32-61-09-000-801 |
| Installation of the Proximity-Sensor Electronic Unit (PSEU) | AMM 32-61-09-400-801 |
| Functional Test of the Proximity-Sensor Electronic Unit (PSEU) | AMM 32-61-09-720-801 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Wire Repair | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Pull and reset the PSEU gear system breakers (CB1-C13, CB1-C14, CB2-C13, CB2-C14), recheck the system for the fault.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Check the PSEU plug, 28 VDC power should be on the PINS 3A and 4A connector A9BP1 and ≥22 VDC. Check resistance to ground on the PINS 3K and 4K connector A9BP1. Repair as required.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Replace the PSEU.
- Functional Test of the Proximity Sensor Electronic Unit (PSEU).
