DD16 western star 4900 500k can bus

Hello guys, recently had a run of a few of our fleet trucks coming up with 500k can bus performance faults causing a wack of problems but they're all extremely intermittent. Any common areas you guys have found issues with ?

Try clear faults then start engine, give about 1200-1400 rpm and tap on cpc module see if you loose throttle or some other faults show up....
If no faults, measure resistance plug #3 at cpc module there is a twisted pair. Cpc should have 120 ohms and on cable 120 ohms.

Hello guys, recently had a run of a few of our fleet trucks coming up with 500k can bus performance faults causing a wack of problems but they're all extremely intermittent. Any common areas you guys have found issues with ?

I have seen on the newer trucks that if there is a People-Net installed or something along those lines that isn't set for 500k baud then they will cause random codes and issues.

Thanks guys, I'll check it out.

They all have a 3rd party gps tracking system installed inline with the factory j1939 connector

Thanks guys, I'll check it out.

They all have a 3rd party gps tracking system installed inline with the factory j1939 connector

Increasing the speed gives you more transfer rate but increases the potential 4 CAN errors 
The physical wiring structure becomes much more strict and less resistant to interference such as 3th party gps tracking system 
Thay do cause issues by them self or bad installation 
Also there is no reason to run 3th party stuff on 500k when you also have much more stable 250k 

You can monitor CAN error rate in Jpro and see if unplugging such devices affects the CAN networks, make sure to reset each time u plug or unplug

I ended up getting to stick in a failed state, found j1939 can low shorted to ground on a bracket behind the fuse panel that a section of loom was pushing down on.