A scantool is a computer with access to technet or whatever GM is calling it this year, like a Tech2. A code reader can scan OBD2 test failures.
In this case the electrical system is being erratic, that would cause every module and sensor to possibly set a code including the CANbus. No useful information to be gleaned, just a bunch of codes. The usual culprit is something in the under hood fuse box or the body harness to instrument panel connector.

 

Not in the world I live in. Never heard that distinction. I've got a code reader, a Clone Tech 2 and a bunch of EFILive FlashScans.

 

You can get a scan tool that will do most anything needed except programming for less than 300. Many of the guys that do their own repair have a scan tool that is good for their vehicle. Not all but many are buying them. The prices are down and the coverage is good. The people that come here are looking for help to do their own work, No. You should be encouraging them to get a scan tool.
The price for the tool will pay for itself in short order.

 

I wish I was rich enough to think $300 was cheap for a tool to use once or twice. I had to scrape $12 together to get a ELM327.
The people that come here for help generally have no idea where or what the OBD2 port is. Many think the battery is the back box under the hood like last century cars.

 

I’ve been instructing folks to go to their auto parts palaces for free code reading, with the caveat to post the codes here not the explanation or part that’s indicated as being faulty for the last 13 years. I have a code scanner, I’ve used a couple of times, I rented an expensive scanner tool to read my abs code last year, it wasn’t the harness as the tool thingy showed but a faulty internal hub connection. So money wasted there if I had purchased the scan tool.

 

FWIW, On most modern vehicles there are many many codes and PIDs that can be read, Some of them are mandated, RPM, MPH, water temperature, others are manufacturer specific, an then there are the changes the tool can make to the vehicle, things like clearing codes. Spending more money at the bottom tends to get better displays and UIs. As you spend ever more, you get access to the manufacturer specific codes and the ability to to change things on the vehicle besides just clearing codes. If you're someone like Snap-On, access to that manufacturer specific information can cost you hundreds of thousand dollars/year, ergo the very high price for "professional" diagnostic tools.

 

You can easily turn your car into a boat anchor.

 

If you only need repairs once or twice in a lifetime you are beyond blessed.
The people who come here by your own definition sound to stupid to help.

 

If they knew how they would not be asking the internet.
I did not use the word "stupid". Uninformed is not the same as stupid.

 

When ambiguity is possible, for clarity, define your terms.