How to diagnose sudden failure of G3X CAN bus?

[David Carter]

Everything was fine when I parked the plane in my hangar a couple of weeks ago. Today everything connected by CAN is red-x’ed out. Some things working in reversionary mode - EMS display on MFD via RS-232 backup, etc.

In config mode, system information device list shows everything on CAN with 100% network error rate, although some devices such as GMU 11, GAD 13, AHRS2 will periodically show green status very briefly.

MFD not showing in device list at all. Perhaps an issue with the MFD, or the CAN wiring to the MFD?

 

[Walt]

Had a customer with a similar issue, harness turned into gourmet lunch for some mouse friends!

 

[Desert Rat]

I had something similar happen. In my case CAN hi and lo were shorted together.

 

[BobTurner]

Had a customer with a similar issue, harness turned into gourmet lunch for some mouse friends!

Had the same issue in my car (canbus eaten by rodents). 4 month wait for replacement part. Dealer told me the insulation was being ‘re-done’. Seems the old insulation was rat-candy!

 

[mburch]

In this type of situation the installation manual is your friend, specifically the step by step guide to CAN bus troubleshooting provided therein.

 

[blaplante]

I would expect that since the CAN bus connects *everything*, then a short/fault could be located *anywhere*. Sounds like fun.

 

[Ron B.]

Everything was fine when I parked the plane in my hangar a couple of weeks ago. Today everything connected by CAN is red-x’ed out. Some things working in reversionary mode - EMS display on MFD via RS-232 backup, etc.

In config mode, system information device list shows everything on CAN with 100% network error rate, although some devices such as GMU 11, GAD 13, AHRS2 will periodically show green status very briefly.

MFD not showing in device list at all. Perhaps an issue with the MFD, or the CAN wiring to the MFD?

Can you PM me since I cannot find how to PM you. Use to PM all the time on the old forum.

 

[AZSteve053]

Everything was fine when I parked the plane in my hangar a couple of weeks ago. Today everything connected by CAN is red-x’ed out. Some things working in reversionary mode - EMS display on MFD via RS-232 backup, etc.

In config mode, system information device list shows everything on CAN with 100% network error rate, although some devices such as GMU 11, GAD 13, AHRS2 will periodically show green status very briefly.

MFD not showing in device list at all. Perhaps an issue with the MFD, or the CAN wiring to the MFD?

I suggest unplugging user devices 1 at a time, best to do this while whole system is powered OFF. Re boot after each disconnect - at some point remaining items will start working.
If you get everything disconnected without finding a bad box - then start troubleshoot harness with EVERYTHING disconnected.
Good Luck.

 

[David Carter]

Thanks everyone for the suggestions. I started by removing the MFD, since that seemed to be one device that wasn't showing at all on the CANBUS, from the PFD's perspective. With the MFD removed, everything went back to working normally. So that seemed to narrow it to an issue with the MFD itself or the CANBUS connection to the MFD. I then reconnected the MFD, and to my surprise, everything continued to work. I assume I must have an intermittent open or short in CAN wiring in that connector. The next step will be to open up that backshell & inspect it more closely.