No Bus code

More than likely this is a PCM but what was the code that you got when you checked them?

This is a pretty common issue on these trucks and it is normally a PCM issue but can also be a cluster issue. We actually have a number of different posts on this exact issue. Unfortunately they don't have a final solution to confirm what fixed their vehicle so it would be good to figure this out.

Basically the no bus message means that the PCI bus network that the PCM, TCM, cluster, and other modules communicate on. The PCM and cluster are the dominate modules so it is normally one of the two of these that fails and causes this message. When one of the other modules fails, it just sets codes but doesn't display this message because the network is still able to function.

I would suggest we start with the codes and go from there.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I am attaching the testing below for this message but it requires a scan tool. So let's start with the codes and go from there.

Thanks

Okay. So after a battery disconnect if there were no codes that is because the memory was wiped.

If it started and ran then I suspect it will be fine until the issue happens again.

Based on all of this, I suspect the PCM is the issue but clearly if it doesn't act up, we will not be able to do any testing.

Just run it until there is an issue and we can go from there. If a scan tool picks up no codes while it says No Bus, I would replace the PCM.