Hello Everyone.
Thanks Scotty for your youtube channel. You provide such an important service. I've learned a lot from you.
I have a friend with a 2013 GMC Sierra 2500 6L gas truck. Approx 60K miles.
He has quite a few codes. He has a p0138- 02 Sensor Circuit High Voltage (Bank 1, Sensor 2). He changed the downstream/post cat 02 sensor on the drivers side and the code came back. I then suggested he swap the rear 02's (put left rear in right rear position and vice versa) and the code came back but another code popped up as well. p0140- 02 circuit no activity detected bank 1 sensor 2.
He checked all the fuses with a tester and none were blown.
In the Drivers info section in the gauge cluster, it says "service trailer brake system"
In addition, he has 3 ABS codes as well.
u0100- lost communication with ecm/pcm
c0561- generic, no definition available
u0137- lost communication with trailer brake control module
I'm thinking he might have electrical problems but I'm not sure. He has owned this truck since new and takes good care of his vehicles. The truck has been problem free up until this point. It looks like it's well on its way to becoming a money pit unfortunately.
Any advice you can offer sir would be most appreciated.
Thank you!
when multiple things pop up like that , it's usually an electrical fault. Chafed/broken/corroded wires, loose grounds, rodent damage, or moisture ingress into the computer.
It is as seem their are TOO many codes and so their is a PCM failure. One strategy is to check the O2 sensor for output directly from a DVOM and then see if the PCM can read it if it was good. If the PCM indicates that its not active then it might be a bad connection from the O2 to the PCM plug in. You would have to verify the data coming in at the plug in at the PCM. If its the same as at the O2 sensor then the PCM is not reading it correctly. Another trick is to disconnect the O2 sensor and see if the PCM can detect an unconnected O2 sensor at the right location. Just some ideas for you to get an over view of whats going on.
