Today my Rockster's ABS test did not cycle as normal, voltage was OK, but getting the 4x per sec flash without the general warning light showing. I found in the Clymer manual that one reason this could happen is a fault in the brake light.  I found the light was burning both filaments, e.g. brake light was on when it was not to, and there was something amiss with the brake light switch.  Turned out the pivot bolt on the foot brake lever was not tight and the spring for the switch had fallen past the stop bolt head, so the light was not switching off. Re-tightened the bolt with the spring now in the right place and that solved the problem.I hope your ABS issue is this simple.