03/15/21
Message Overview:
Message Description:
PSEU detects an OPEN circuit within the proximity sensor PX40, Left Nose Gear Door Closed, or in the wiring to the proximity sensor or aircraft.
Possible Causes:
- Nose Landing-Gear Downlock 2 Proximity-Sensor (PX40)
- Proximity-Sensor Electronic Unit (PSEU) (A9)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Operational Test of the Proximity Sensors | AMM 32-61-00-710-801 |
| Functional Test of the Proximity Sensors | AMM 32-61-00-720-801 |
| Removal of the Nose Landing-Gear (NLG) Proximity-Sensors | AMM 32-61-05-000-801 |
| Installation of the Nose Landing-Gear (NLG) Proximity Sensors | AMM 32-61-05-400-801 |
| 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.
- Verify the wiring from the PSEU A9CP1 PIN 7F to PX40P1 PIN 1, and from PSEU A9CP1 PIN 8F to PX40P1 PIN 2.
- If the wiring checks good, download and have field service review the PSEU NVM. Further troubleshooting will depend on results of the PSEU NVM.
- If the fault is still there, replace PX40, and then check the sensor.
- If the fault is still there, replace the PSEU.
- Functional check the proximity sensor electronic unit.


