eltorro

I have been dealing with an intermittent abs light for a few months..
I'll spare those details and tell you what is happening now..
The light is solid..when I disconnect the battery for over one hour and
reconnect the abs light comes back on right away with no driving..
I get 3 error codes..when it was intermittent there was just
one..17..it was very intermittent..
Appears solid now..error codes 15,16, and 17..
I disconnected the 2 cables going to the modulator and cleaned them....no help..
I'm not sure where the sensors first connect to the abs 'computer'.
Any suggestions??..I can only explain the multiple errors as a
defective control unit or a floating ground someplace..