ABS on-again / off-again

[KIERAN A. LAVIN]

This was kind of weird over the weekend.  It's on a 95 200SX SE-R and I'm
just wondering if anyone's seen it before or has any ideas before it
happens again and/or I get around to troubleshooting (I'm just trying to
expedite my 'fixing' process ;)  The archives just yield way too much BS
so...

Friday night I was following someone on a 3-lane road with traffic lights.
A light ahead changed and the person in front of me slammed on their
brakes.  There was plenty of room for ME to make it through the light so I
was accelerating until I saw the person in front slam on their brakes.
THEIR brakes locked up good and so did mine (well, I have ABS but the pump
went and I just held on for dear life).  For reference, there were cars in
either lane around me so I was kind of boxed in.  I drove probably 150-200
miles after that with no other incidents with the brakes outside of normal
stopping and slowing down.

Yesterday I washed my car at a DIY place.  As I pulled out toward the
street and slowed down, my ABS went off.  I thought nothing of it as it
must've just been some soap/water on the rotors/pads.  I drove another 20
miles or so with nothing out of the ordinary brake-wise.  Until last
night.  As I was leaving my fiancee's, at the end of the street, the ABS
went.  I got to the end of the next street and had the same result.  I'm
now pulling onto a 40MPH side street and tested them out.  Every time I
slightly hit the brakes, the pump would set off.  I hit the brakes hard
and it pulled to the side (unfortunately, I don't remember which side so I
didn't know which side to check!)  I slowed to pull onto a sidestreet to
jack the car up and take a look and the ABS light went on (disabling the
ABS) and the brakes went back to normal.  I aborted checking everything
out because I was tired and I got back on the road.  Later, I had an idea
and I turned the car off and on while driving to see if it'd reset.  It
did.  I tapped the brakes and everything was normal.  I drove another 50
miles or so with the ABS light off and the brakes working normally.  I
thought maybe it'd be a sensor on one side?

When I was having the issues last night, even when I was off the brakes,
there was a slight scraping/humming coming from the right side.  The past
few weeks I've heard a very, very low/slight humming that I cannot figure
out.  At first, I chalked it up to loud tires and it being road noise.
Then, after having a pulsating when applying the brakes moderately (I
hadn't had a chance to SLAM on the brakes to try to burn whatever off
until that emergency stop on Friday) I checked rotors and brakepads and
everything looked fine.  Till now... that mild scraping/humming that's
almost inaudible (except to the owner... as it always is!) is still there.
I'll have to dig into the ABS section in the FSM but was wondering if
anyone's encountered this?  Kind of weird and scary if it happens in a
hard-stopping situation unexpectedly because when that pump was running,
it wasn't really slowing the car down all that much under moderate
braking!

kieran