CAN C Bus Issues

[Delano1981]

Hello Everyone,

I think I am having CAN C bus problems on my 2007 Ram 1500 15.7L. I recently purchased an Autel ML629 scanner, but it won't communicate with the Transmission as it is supposed to. I checked the CAN network from the DLC in the cab connecting to pins 6 & 14 and ground with my Picoscope, and what I got does not look right. The blue trace is CAN high and the red trace is CAN low. I have attached two pdf files showing the wave forms, one with key on engine off, and one with engine running. There are no trouble codes or check engine light. Anyways, I am very new and inexperienced with auto diagnostics, I am just learning as I go and watching videos online.

Thanks

 

[GTyankee]

I know less about the Can Bus systems that most people

But i seem to recall reading that Can C was first used in the 2009 Ram 1500 & the Jeep Grand Cherokee
They needed it because of the number computer chips that have to communicate with the CPU & indirectly with each other

I remember this because the 2009 Ram 1500s & Grand Cherokee radios were not compatible with the rest of the 2009 vehicles in the fleet

2009 Ram 1500s & Grand Cherokee radios were High Speed Radios
the rest of the 2009 fleet were Low Speed radios

 

[Delano1981]

Thanks for the reply. I am going by the 2006 Ram factory service manual. I have attached a page from the manual about bus communication, which does show a CAN C system. I don't have the 2007 factory manual, do you think the 06 manual is compatible with 07?

 

[GTyankee]

Yes they are compatible

2002 - 2008 are pretty much the the same
then there were some minor changes 2006 - 2008

 

[Delano1981]

I did some more testing this morning. I disconnected the battery and reconnected it and got a normal CAN signal at the DLC. But, after cycling the key off and back on, it went back to an abnormal signal. The top image is the normal signal, and the bottom one is the abnormal signal.