Garmin Can BUS Testing

[snoop9erdog]

Is there a recommended procedure for testing the CAN BUS circuits prior to sealing up with shrink wrap to catch any issues? Prior to finishing the backshell connections. Can someone recommended what they did to ensure good connections? Thx

[upperdeck]

I know that if you boot up the g3x into config mode, it will show green check marks next to all the devices if they are online. It will also show the can bus stability as a percentage.

I can also tell you from experience that all green check marks is no guarantee. I had a blob of sharp solder poke it's way through heat shrink and make contact with the back shell grounding out the can bus after about 20 hours on the airplane. It promptly crashed the can bus but in an intermittent fashion. Took hours and hours of trouble shooting to chase this issue.

[g3xpert]

Originally Posted by snoop9erdog

Is there a recommended procedure for testing the CAN BUS circuits prior to sealing up with shrink wrap to catch any issues? Prior to finishing the backshell connections. Can someone recommended what they did to ensure good connections? Thx

Hi Ed,

There is a CAN bus troubleshooting section of the G3X Touch Installation Manual
that will be helpful, 2.3.1.3.6 CAN Bus Troubleshooting, starting on page 2-26.

Please let us know if you have any questions. You can always email us at G3Xpert@Garmin.com if you would like.

Thanks,

Justin

[PilotjohnS]

The easiest check is to check for shorts as you build.
As you build up each connector:
1) ohm check from canbus high to canbus low and make sure it is open.
2) ohm check from canbus high to connector back shell (ground) and make sure it is open
3) ohm check from canbus low to connector back shell and make sure it is open.
4) check from the newest connector that you just got done building up to the previous one for continuity from canbus high to canbus high, and from canbus low to canbus low.

5) when you are all done, check from the last connector to the first connector continuity from canbus low to canbus low; and canbus high to can bus high, and open from canbus high to ground and canbus low to ground.

Do these checks before pulling the connectors into the boxes and before power up everything.

[snoop9erdog]

Thanks for the comments. I checked the continuity and shorts last night from the right wing mounted GMU 11 to the Roll servo and all was good. That's a good check practice sequence John, thank you.