yep kevin is right on the money there
bad relays have been problems in the past with these systems
swap them around and see if the problem changes or goes away
in the lid of the relay box it should tell you which relays are the EGI relays which are usually the culprits causing those error codes

i'd also check the ground to frame where it bolts to the frame behind the ecm. Physically remove the bolt and check for painted surface underneath, some units had issues with ecm communication errors and we found that the surface was painted over and we had to scrape the paint off to get a decent ground to the system to get the errors to go away.