98 Blazer ZR2, brakes slip, like anti-lock is engaging when it shouldn't

[IndianaAbsentee]

That's about the best I can describe the problem. When I am driving slowly (under 10MPH) and I press the brake pedal, the pedal gives feedback like it would if the anti-lock brakes were going off. However, I don't here the anti-lock system engaging, and the truck doesn't stop.

If I am having this problem and then I SLAM on the brakes, it stops.

To make it better, the problem only happens maybe once a day, and otherwise the truck stops fine.

It can cause some real problems though as I ran into a tree along the side of my driveway last week because as I turned into the driveway to park, the brakes acted up. I just bumped the tree, but I've had a close call or two in parking lots as well.

Any suggestions? Anyone else have similar problems?

[MT-2500]

You might want to look at speed sensor wiring but.
You will need to get it on a abs capable scanner and get the code to point to the problem.
Best time to catch it is right after it does it and a code is set.
Do not turn key off before you check for codes.
They will reset after key is turned off.
Post back code no.

[BlazerLT]

Get it to the dealer ASAP and don't mess around with this or you will end up dead.

Could be the ABS module, a speed sensor, or many other things.

Get it to a place that can scan for ABS codes.

[old_master]

"If I am having this problem and then I SLAM on the brakes, it stops."


Sounds like a possible problem with the master cylinder. If you push hard on the pedal, does the pedal hold or slowly creep down to the floor? If you let off a little pressure, does it still hold, or creep to the floor?

[IndianaAbsentee]

Ok, it was posted that codes will reset after the key is turned off, and that the best time to check is right after the problem happens.
I don't have any kind of indicator light coming on (ABS light, BRAKE light) on my dash, and the problem is VERY intermitent. Will this cause a problem to a dealership pulling codes?
Also to Old Master, the pedal seems to react normally 99% of the time. There is not any creeping or sticking. It just occasionally gives a very obvious (you can hear it and feel it from the passenger seat) feedback when I'm braking from a slow speed. Paying closer attention to it recently, Slaming on the brakes doesn't make the feedback stop, but it does make the truck stop moving.
Sorry about poor explanation guys, this is odd to me and hard to describe.

[IndianaAbsentee]

Wanted to add something else. . .When I posted this originally I said the pedal felt like the anti-lock brakes were going off. I got on an icy parking lot recently and purposely set the anti-lock off so I could compare the feeling/sound. It's not the same. The resistance from the pedal is the same, but I could hear the anti-lock system working. With the problem I'm having, I hear something that sounds like it could be the brakes slipping or jumping.
Thanks again

[old_master]

The fact that neither light comes on when the problem occurs might indicate that the ABS and master cylinder are ok and the problem is elsewhere. Have you removed the wheels and visually inspected the brakes? The friction material may be worn off allowing the pad to grind against the rotor. That could explain the noise and poor stopping performance.