Why is the relay wiring module not communicating?

How would I know the thermostat is unable to communicate with its relay wiring module?

IMPORTANT: The wiring module not communicating with a thermostat does not mean the thermostat or relay module is bad..

The relay wiring module comes built into your Pelican thermostat, but can be removed and co-located to assist in wiring a Pelican thermostat in a limited wire application. There are two indications that the wiring module is unable to communicate:.

On the TS thermostat’s display you see an X (X with No Dots) in the upper right hand corner. On a TC thermostat a notice will appear in the upper right. When clicking this notification, it will say “check your communication wires (R,C,D) between the thermostat and wiring module”
You will also receive a notification on your Pelican web-app stating: “Thermostat Name (Serial No: XXX-XXXX) Check Wiring Module.

From the app, you can navigate to the thermostat’s configuration page, scroll to the bottom and select Signal Outputs: if you see an X next to Relay Wiring Module under Communication Status then the thermostat is unable to communicate with its relay module. This will turn to a check mark when communication is restored.

Troubleshooting a thermostat communication issue with its relay wiring module:

Here are the steps to take to fix the communication issue:

Confirm that the correct wires between the relay wiring module and the thermostat are connected. (R) must go to (R). (C) must go to (C). And (D) must go to (D). Note: The thermostat may power on if the (R) and (C) wires are backwards, but the thermostat will be unable to communicate with its relay wiring module.
Verify that the (R), (C), and (D) terminal blocks are making good connection with their wires.
Check the relay module’s light. If it is flashing (blinking quickly), there is a communication issue. It should be Off for short periods of time and only blink every once in a while (the random blink indicates active communication between the relay module and the thermostat).
Check that there is at least 21 Vac between (R) and (C) at the thermostat and at the relay module.
Make sure there is no Z8 or Z24 wired to the (D) wires from the thermostat to the relay module. A thermostat is NEVER wired to a Z8 or Z24.
If you are still having problems, recheck your wires.
If you are still having problems, contact Pelican technical support for further assistance.