These two things don't really add up. If the alternator failed and the voltage was getting low, I would expect there to be a lot of low voltage DTCs. However, to answer your question, if the voltage drops below a threshold then the modules will start malfunctioning and it will do what is called load shedding. This means it starts cutting off operation of lesser systems so that it can keep voltage for more necessary items. This could explain what is happening.
I would suggest, replacing the alternator and battery if needed and then retesting.
If the ABS, traction control lights and others come on then there would be codes. I suspect the parts store's scan tool was not able to communicate with the ABS module. Some tools are not able to do this and if that is the case, then it would explain why they didn't get any tools. There is another possibility that the ABS module is offline and they just couldn't communicate with it. Again, a shop with an actual scan tool and not just a code reader will be able to tell if this is the issue.
Nevertheless, if the lights are on, we will need to find out what codes are in there otherwise we will be guessing at this.
Let me know what happens after you get a known good alternator on there are we can go from there. Thanks
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Monday, June 10th, 2019 AT 5:01 PM