I have read that one can take off the negative battery cable to reset the check engine light and it will go off for a short time. Is this correct?
Maybe but you will probably lose codes that you don't want to. It is better to use a OBD2 code checker to read the codes and then reset the light. The light will come back on if you don't fix the problem.
You have to leave it off for a while, few hours. It will clear everything but will not be ready for testing until enough cycles and miles it retests everything and the code will just come back if its an issue. Most parts stores will read and clear the codes for free, its honestly faster and less effort than waiting for the battery, plus you'll get an idea of what the problem might be.
You may loose programming of the PCM if you disconnect the battery, and would not get it started. Everything would have to be reprogrammed to get it started. Use a scanner like F.O.R says too.
Looking for a Used TrailBlazer in your area?
CarGurus has 4,567 nationwide TrailBlazer listings starting at $1,475.
Search Chevrolet TrailBlazer Questions
Chevrolet TrailBlazer Experts