Various dashboard lights are on after preventative maintenance

My 2004 Toyota Avalon is at 100,000 mi so I did
some preventative maintenance which included
installing the water pump kit, which included the
timing belt, been changed the other two belts that
run my car. After that all of a sudden my engine
light and my trac off light and VSC (or something
of that nature) lights are on. Those lights have
never been on before and we're never on prior to
the repair. The car seems to be running fine but I'm
still a little leery. I know there is a reason that all
three of those lights came on. Any help?? I read
some people posted to unscrew their gas cap and
undo the battery , I did those things already. The
lights turned off for 10 minutes and then came
back on.