99 sierra abs problems....

I have a 99 sierra 4x4, 5300 V8. When braking, no matter what speed,
my anti-lock seems to kick in at 5mph. Doesn't matter on road
conditions, weather, or temp. Even worse, if I happen to hit the
brakes at exactly 5 mph, the pedal seems to really 'lock' up and I
can't stop without frantically pumping the brakes!!! This is a real
problem when trying to pull into a parking spot at the store. I've
read some old post about earlier abs probs on the GMC's and was hoping
someone could give me some insite on my problem.

Thanx,
Mhud

I heard there is a GM bulletin stating to check the ABS wheel sensors where
they are mounted.
It seems there is rust buildup and it is heaving (lifting) the sensors and
that causes a intermittent wheel speed reading.
Take out the sensor and clean the surface where it is mounted, you might have
to use a hammer and a screwdiver to chip away any rust that is present, then
make sure you paint the metal to minimize the rust from coming back.

Regards
William