Cat D6K2 random electrical fault.

The dozer I run has had a random electrical fault all summer. It'll run perfect for several weeks to a couple months then over several days it will act up every little bit.
The symptoms: the first thing I notice is the GPS system will shut down. When I go into GPS diagnostics the only thing showing as connected is the CB460 control box. Both MS992 receivers, the SNR930 and the Cat ECM all show disconnected.
Next the yellow diamond warning light on the dash will light up. When I check the faint codes the fault codes on the machine dash it is showing 872-09 and 246-09.
Sometimes when this problem is active the machine will suddenly totally shut down momentarily like I've turned the key off and immediately turned it back on. Usually when this happens the problem is "fixed" for a long time. Other times the problem disappears for a while on it's own.
I've checked every harness and connector I can get to and I'm out of ideas.
Any help from the Cat gurus here will be greatly appreciated!
The machine serial number is CAT00D6KAWMR00579

Machine dash showing fault codes that were active.

Both of these Codes are in the Machine ECM (MID 039)
CID 0246-09 is the Proprietary CAN Data Link
CID 0872-09 is the Pitch Rate Sensor
FMI 09 (common to both) is "Abnormal Update Rate". This relates to the communication between the electronic controls over the data link. FMI 09 occurs when an electronic control is not able to receive any information from another electronic control, when the electronic control expects to receive said information.

Unfortunately there are no detailed troubleshooting procedures for these two faults. TBH there seems to be little in the way of anything related to troubleshooting the Accugrade system.

I'll send you an Electrical Schematic which includes the Accugrade wiring. First stop should really be to check the wiring and connections from the Pitch Rate Sensor to the Machine ECM. It may be nothing more than a loose/damp/corroded connector.

Thank you very much Nige!

I'll post this for others who may face the same problem I've been having.
I got lucky today.
I called SiTech and they had a tech who would be driving past our job site an hour after I called.
He checked the CAN data link first. The voltages were wrong. Then he unhooked the SNR930 and the machine shut down and restarted on its own. He plugged in a spare SNR930 he had on his truck and everything came up and connected. He unplugged his and plugged our SNR930 back in and all the problems returned.
So I'm up and running again.
Now I'm curious about CAN data link. Can someone explain it in plain English for me please? I understand all controllers are communicating via CAN. What happens when one item like this shuts down the whole network?
Thanks again to everyone who posts on this forum! I've learned a lot reading your posts.

My reason for wanting to understand CAN better is for troubleshooting purposes. I carry a set of tools and a multimeter in my pickup. My bosses like it if I can get the machine working again. At the very least with these intermittent issues it's nice to know what to check and what voltage, amperage, resistance, etc to expect in the moment it's not working...