ABS light flashing - 1990 Silverado

I am the original owner of a 1990 Chevy Silverado and a few months ago the ABS light started flashing.

1 long - 8 short flashes.

My local chevy dealer told me that the 90 models were a little 'squirley' when it came to abs and showed me how to reset the abs system by unplugging the abs computer mounted on the master cylender. That stopped the light from flashing - but only for a few weeks. It has returned.

Anyone else had this issue?? What solved it??

I can't believe that a warning light goes off for no reason.

Thank you all for your responses.