ABS and Brake light on

Hey guys, I have a 2004 Chevy Silverado 1500 crew cab.

I was driving and occasionally hitting bumps my abs and brake light would flash on.

One day I did it and my alternator voltage dropped to nothing on the dash like 9 volts.

I replaced my alternator it was pretty old anyway and bearing was noisy so no big loss but that didn’t solve my issues. I know low voltage will cause those lights as well sometimes

Anyway I checked my ground under the driver door by the body mount and cleaned the surface and front ground by the bumper cleaned and reinstalled them.

Ground on driver side head is still attached I snatched on it decent and no looseness

I’m starting to think it’s the ABS module because I can’t communicate with any of my computers

The obd2 port powers my scanner but won’t communicate with anything just fails too

I unplugged my abs module since it said doing that could prove the module is bad if I can then communicate but no change still error to communicate codes

Any suggestions? Anyone been here before