Today, while refilling the washer fluid on my 1998 Malibu, I noticed that
the sensor that goes into the side of the master cylinder looked like the
connection was loose.  When I pulled on it, the sensor part pulled right out
of the plastic body it was supposed to be connected to.  It was some type of
resistor, wrapped in a white plastic coating.

What I want to know is what is this sensor called, reason being, the ABS
light has been on in this car since I bought it 1.5 years ago.  Last year I
replaced both front wheel bearings and all of the front brakes, the rear are
still about 1/2 wore.  Once the bearings were replaced, the ABS light went
out for about 3 months.  After that, it began to randomly light while on the
highway and I didn't think anything of it because the brakes still operated
fine without the ABS system.  Every now and then while it was lit, the red
brake light would also light for about a second and then go out, the ABS
light would continue to stay on.  Now that it is warm, the ABS light stays
on as soon as I start the car.

I was planning to bleed the brake system and put new fluid in it anyhow, but
would this sensor being loose have any effect on the ABS light staying on?
I did some quick searching, but came up with nothing.  Also, once I find out
what this sensor is, will I have to drain the master cylinder in order to
change the sensor, or is it simpler than that?

Any help is appreciated,
Sharky