How do I troubleshoot a non working Plenum Pressure Sensor (PPOT)?

This article will walk you through the troubleshooting steps of a non working/reading Plenum Pressure Sensor (PPOT)

Advanced Troubleshooting of a PPOT that is not reading.

1. Unmap the Fan Node Radio (FNR) unit to which the PPOT is associated/connected with/to
2. Unplug it from the Fan Node (FN) terminals (PPOT – 3 x wires – see image)
   
   
3. Check for voltage on the PPOT+5 V (DC)
   

   With a multimeter/Voltmeter measure voltage between PPOT COM terminal and PPOT 5V terminal: voltage should be +5 VDC ± 1

4. Check for short circuit on the PPOT subsystem.
   With a multimeter (selector on continuity -see attached image) measure for electrical continuity between wires.
   
   
   
   

   Should not beep on any of the measurements, otherwise, it would mean either wires on short circuit à INT3 replacement needed, and/or faulty PPOT à PPOT replacement needed

5. Check for electrical continuity on each of the 3 wires and/or short circuit:
   
   - Open the PPOT device: remove the front cover by unscrewing the four screws,
   - Use a multimeter (Selector on continuity – see figure) and check for continuity as         illustrated in the following image.
   If need be (wire ends not reachable with the multimeter leads), short circuit two wires at a time on either of the ends (FN end or PPOT end).
   
   
   

   Measurement on all 3 wires should beep à short circuit, otherwise, it would mean an open wire --> replace the INT3 cable

6. Cycle the power on the Fan Node (FN) unit by unplugging for about 10 seconds the wire connected to the VCi+ terminal and then, plug it back in
7. Remap the FNR and wait for about 20 seconds after it has been mapped, and
8. Check for PPOT readings (Pressure and Temperature): if no readings (or error message), that would mean either faulty PPOT or faulty FN unit (PPOT port)