GMLAN errror

[TAG_SK]

I have a 05 Corvette A4, it runs great, but I have a problem using a data logging tool or code reader- unable to read vehicle information. I took it to a shop that had a snap on scan tool and was able to get 3 codes; P0700 Transmission Control Module Requested MIL illumination, U2100 Controller Area Network Bus Communication, and U2105 Lost Communication with Engine Control Module. Codes where cleared and later that day I was able to log some data, but the next day I tried again and was unable to get vehicle information again. I noticed when the shop's scan tool was connected and then disconnected the driver information center on the dash alternated between Service Active Handling System & Service Traction Control System, but after a restart they did not appear again. What do I need to do to fix this?

 

[c4c5specialist]

HI there,
First off, CAN network is totally different from Class 2 scan code readers.
So, if your code reader is not CAN compatible, you will not be able to read codes.
Second, your u2100 is showing that the CAN network is being shut down for some reason.
Now, aftermarket scan tools will sometimes create the type of reaction that you saw in your DIC.
A Tech 2 will not, but some others will, so I would disregard the function.
Concentrate on the codes and the ECM. DISREGARD YOUR P0700, as this is a byproduct of the CAN failure.
Power sources and ground sources need to be checked first.
Then, the 2 wire CAN network wiring would need to be verified also for integrity.
THIS IS NOT SOMETHING for a technician that does NOT KNOW THE VEHICLE>
They need to be fully trained on the CAN network to accurately diagnose it.
There are no bulletins or PIs for your particular problem.
Allthebest, c4c5

 

[TAG_SK]

Thanks for the reply. My code reader and data logger are CAN capable. I checked the grounds and they are good as is the power. I will be taking it in for service to check out the data wires.