I don't think the cause is related to specific voltage. I just grabbed a PDP off the shelf and it seems to maintain LED functionality as I sweep the voltage 0 to 15 and back.
If anything, perhaps the smart module has intermittent contact with the rest of the PDP. If you press down on the Weidmuller CAN connectors, or press down on the LED light pipes, does the smart module suddenly come back (LEDs become illuminated again)?
If anyone else is seeing this symptom feel free to contact us at
support@crosstheroadelectronics.com.
Joey, I just replied to your email. Looks like I'm not far off from where you guys are located.