Can a dealer diagnostics test show all problems with a late model (2003) vehicle, or does a defective part have to be replaced in in order to locate another problem in the same circuit. Example: Does a bad ABS wheel sensor have to be replaced in order to find a bad ABS module? I would think that a diagnostics test could override a bad wheel sensor and show it as working in order to continue checking the whole circuit. If this is not the case, it should be corrected. With all the technology available today, I wouldn’t think that would be a problem.
If it’s either / or, there isn’t a problem. You get all the codes at once anyway. Will there be problems that aren’t solved right away? Yes! Problems don’t change their ways over the years. No matter what technology you have, you can’t prevent every problem from happening whenever it wants to happen.
Technology doesn’t solve problems, it causes them.
Maybe you could just tell everyone what the back story is here. Trying to get answers about abstract, in principle cases probably won’t help you very much.
In a general sense, though, don’t overestimate the abilities of the diagnostic computer equipment for cars. They really just collect data.