01 Ram 1500 Sport 5.2L (318cid) 4X4.
So, as stated in title.
I replaced my ECM and my O/D started working whereas it did not before.
ECM never crossed my mind as the culprit for O/D problem. The ECM came with the truck, and I just never swapped it out until recently.
The replacement ECM seems to have made the truck overall better. However I now have a no bus message, and cel is on with no codes when using a scan tool.
I will also mention that my overhead digital display does not function properly. I have read that this is one of the many things communicating with the ECM. Could this be the source of the no bus message?
Also, I would like to know the program of the original factory ECM and the new ECM. Is there a way of looking it up according to the label on the unit?
I will attach image of factory ECM,
I do not have the replacement in front of me at the moment, as it is on the truck.
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This is factory ECM from a 2001 Ram 1500 sport.

 

So far as I know, there is pretty much zero information on that various programming on the different PCM's. Aside from folks that actually do tuning, whether as a business, or just personal use, Dodge is likely the only folks that have that info, and they ain't sharing.

That said, inop o/d is unlikely a programming issue, and more likely an internal failure in the PCM. The pcm just grounds a specific circuit when certain criteria are met to engage O/D. Of course, if the PCM thinks that is should be doing that, but nothing happens, that should set a code about 'solenoid performance', or some such.....

Could the overhead display cause a no-bus? Probably. Unplug it, see if that problem goes away.

 

Thanks for the reply
Makes sense what you say about PCM and O/D.
I swapped them back out, and now with the original factory ECM in place, there is no cel, no bus message is gone and ,OD once again is not working. I have not disconnected the overhead display with the new ECM, however with the original, there is no longer a no bus message.
And I may be wrong, but wouldn't disconnecting the overhead display CAUSE a no bus?
As the ECM would not be able to communicate with the overhead.
But I'll give it a shot.
And I have never had aan od/tcc code on this truck.
On my previous 2000 ram I DID have the od/tcc solenoid code but the od worked.

 

Look up your original PCM by part number. It should mention something about what trans is expects..... Wonder if it was replaced before, and came with something that didn't have an O/D trans????