03/15/21
Message Overview:
Message Description:
Discrete Input 06B Power Take-off Unit Low Pressure (PTU Low Pressure) circuit failed.
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 for 28 VDC on PSEU A9BP1 (pins 3A, 4A, 3C, 4C, 7K, 8K, 7H, 8H) and Ground A9BP1 (pins 3H, 4H, 3K, 4K, 7A, 7C, 8C). Repair as required.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Do wiring check between PSEU A9CP1 (pins 1B, 2B) and IAPS A4P1 (pins 61, 62). Repair as required.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Do wiring check between PSEU A9CP1 (pins 1B, 2B) and DCU A14DP1 (pins 1A, 1B). Repair as required.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Do wiring check between PSEU A9AP1 pin 14J and MT121P1 pin 1 (PTU MT121). Repair as required.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- If possible, download and have field service review the PSEU NVM. Further troubleshooting will depend on results of the PSEU NVM.
- Replace PSEU.
- Functional check the proximity sensor electronic unit (PSEU).
- Do close out.


