Checks / troubleshooting:
1. The communication cable may be malfunctioning.
2. F/W on Heater controller board maybe malfunctioning.
3. Junction board may be malfunctioning.
4. Heater controller board may be malfunctioning.

Recommended actions:
1. Check the connection of the communication
cable.
2. Replace the communication cable.
3. Replace Junction Board Assy.
4. Replace Heater CONT board Assy.