I don't read codes anymore. I just go under the hood with my ohms meter and read the two front plugs. The one that doesn't "read" is bad and gets replaced. Sometimes you don't even need the meter because a visual inspection of the lead will indicate which lead is bad. If the rubber has cracks or is partially missing that is usually the one that is bad. If it has those issues and they are not addressed then they will go bad.
Back to reading the codes. With the ABS leads "Right" is "Left" and "Left" is "Right". For all other things GM sitting in the drivers seat left is left and right is right. With the ABS when you are facing the engine right is right and left is left which makes what I said earlier clear...