These trucks run on a local area network (LAN) for comms between the modules, and as such it's vulnerable to interference due to bad shielding, weak terminal connections, etc. There are methods for troubleshooting the LAN comms, so that's where I'd start.
Diagnosing High-Speed LAN Concerns
Diagnostic tips may to help locate the source of a loss of communication with a high-speed LAN module.
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