All codes
Service call
SC665
Serial communication error
BCommunications
Level B — stop, power-cycle may clear
First check
What was just installed? New option I/F is the usual story.
What it means
A serial peripheral (meter, option, controller channel) dropped.
Likely causes
- Option I/F
- Controller UART
- Cable
On-site steps
Parts to have on the truck
- Option I/F
- Controller
Related codes
Confirm the subcode and part number in the FSM for this serial. Raicoh is a field companion, not a replacement for the book.