The 95 Buick Century is wigging out.
When the brakes are applied it seems like the ABS is kicking in and releasing the caliper (s?) causing a very unusual braking condition. It stops, but it is a very unnerving feeling like the brakes will be letting go. they then recompress and it stops. Duration is about a second or 2 of free rolling. The "Low Traction" light comes on during this process. During longer braking the system seems to pulse on, then pulse off.

There is no pedal feel during the release.

I'm pouring thru the Haynes and cant locate this problem identified.

I cant tell if it's one side or both, in the front or rear.. I was outside the vehicle while braking was applied and I cant hear or see anything abnormal on any corner.
It happened once on sunday, a couple of times yesterday- but is consistent during brake application today. New front rotors and pads were installed about 3 -4 months ago.

Would a bubble in the brake line cause this to happen? I dont see any fluid drops or leaks from any wheel and the brake fluid level in the resevoir looks to be at a normal level.

TIA- any ideas?

 

the abs runs off of a trigger on the half shafts in the front. I would check to make sure they are/ lined up correctly
/ cleaned off
/ there....

 

I'll check that now- Thanks buddy!

 

The problem is two letters...GM.

Seriously it sounds like an ABS sensor is sending false information.

 

Has the system been bled lately? That is the second thing I would do (after a thorough inspection (see below)). Flush out all the old fluid and get fresh stuff in there. Air bubbles in the system may be the cause of the issue you cite.

Alternatively, I would test with the ABS system disabled. This will help to eliminate the base brake system as the problem. There should be a fuse or relay that can be pulled to accomplish this. If the base brakes are effective than you will want to focus your attention on the ABS. As mentioned above (xsboobs?) check the senders and tone rings. They must be clean, aligned and properly gapped. Look for debris in between teeth on the tone rings. This is fairly common.

Good luck.

 

The Haynes states: yadda yadda yadda, It is necessary to use a Tech 1 diagnostic computer (#94-00101A) linked into the ALDL to access these codes. Any failures in the ABS system should be repaired by a dealer service department.

Is this similar to an OBD II reset, or a different animal completely?

The Haynes mentions the wheel speed sensors, but no indication of the actual location or any illustrations of them.

Half Shafts.. meaning inboard of the CV's ?

 

What is it with the daily drivers? The check engine light is on in the Dodge today. I popped the the hood and checked and the engine is still there.
I'm just gonna ignore it.

 

MY daily driver is A-OK, I thank you very much..

Check engine.. LMAO Pete.

 

Here is a little more info on the symptom.. This is crazy..

Hard braking is fine, ABS does not lock the brakes when forced to hard braking and does not interfere or seem abnormal. .

The brakes seem to "let go" but not fully if a little more than marginal brakes are applies. I can feel this in the pedal now. There is a small clicking/ grinding noise when the "traction control" light goes on. This noise disappears when vehicle comes close to a complete stop, and the traction control indicator goes off. At about 2 mph.

the feeling of lack of braking only happens between 7 to 3 mph., unless the brakes are applied very lighyly to allow the car to come to a full stop.

 

the abs runs off of a trigger on the half shafts in the front. I would check to make sure they are/ lined up correctly
/ cleaned off
/ there....

If they are not there, or lined up (which is not possible) the ABS light will be constantly on.

Is this similar to an OBD II reset, or a different animal completely?
A Snap On or similar hand held scanner with ABS module can scan, that is what they are referring to. This is a 95 and should be OBD1 but it will be read through the same serial link port.


Half Shafts.. meaning inboard of the CV's ?
Same term different part, the CV is the actual stub joint, the half shaft refers to the shaft itself.

There should be a donut type device on ONE axle (probably passenger side on that car), it looks like a large black donut, that goes around the body of the shaft. The tone rings are driven on the CV or brake rotor (not sure which on that model), it looks like a castellated nut only with more grooves. The sensor should be very small and setup directly across from the tone ring (i.e. the sensor takes a reading from the spinning tone ring, much like a cam sensor).

It sounds far more like an the accumulator is going bad or has air in it. Step one, bleed brakes. If you have air in the accumulator they can be a real bitch to bleed (the notable exception is Jeeps where a diag. scanner is 100% necessary as the only way to bleed the brakes is with the scanner).

I assume you are coming to the FEST, bring it and I will see what I can do with it.
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