Wierd Brake Problem...

[pappyl]

Ok this one has me stumped....

note: Recently (3 wks) changed out the LF bearing (the RF bearing last year).

Symptom:(Just started) When braking to a stop (under 2-5km/hr) brakes will "lock up". This is intermittent and not consistent. Noise is made (like traction control or ABS engaging) very briefly. Brake pedal drops a bit. Car lurches to a full stop.
- No fluid loss
- Does NOT pull to one side or other (thought problem was caliper locking).
- the LF wheel does have a slight clicking sound (I think its my new bearing?) on a manual rotation

Jacked up front, brake test, and manual rotating tires, neither locks/drags. Visual inspect - both release fine. Pulled calipers and greased up pins/sleeves - movement good.

I am thinking...
- The ABS is engaging because it is thinking wheels are not spinning together - because the bearing is NOT sending the electromagnetic current pulse.... Problem with my new bearing?

Looking for ideas before I give up and bring it to garage...

[myfirstbonnie]

Any lights on in the cluster that shouldn't be, ABS, brake etc?

[pappyl]

no lights.... nothing showing on scanner....

[hohosr]

This happens with mine when I dont run it for a couple days. Its obviously an issue with the ABS because very little pressure on the pedal locks the breaks down and the classic vibrating in the break pedal from the ABS. It only happens to me on gravel though. Is this the same for you or is it doing it on pavement as well? Consider replacing the ABS module maybe? Should be able to find one on ebay or in a junk yard.

I am not a mechanic nor do I have any formal training however I perform all of my own work on my vehicles. This is the first step I would personally do. I like the challenge of learning.

[renchjeep]

Ok this one has me stumped....

note: Recently (3 wks) changed out the LF bearing (the RF bearing last year).

Symptom:(Just started) When braking to a stop (under 2-5km/hr) brakes will "lock up". This is intermittent and not consistent. Noise is made (like traction control or ABS engaging) very briefly. Brake pedal drops a bit. Car lurches to a full stop.
- No fluid loss
- Does NOT pull to one side or other (thought problem was caliper locking).
- the LF wheel does have a slight clicking sound (I think its my new bearing?) on a manual rotation

Jacked up front, brake test, and manual rotating tires, neither locks/drags. Visual inspect - both release fine. Pulled calipers and greased up pins/sleeves - movement good.

I am thinking...
- The ABS is engaging because it is thinking wheels are not spinning together - because the bearing is NOT sending the electromagnetic current pulse.... Problem with my new bearing?

Looking for ideas before I give up and bring it to garage...

Which wheel is locking up, if any?

Check all 4 wheels for binding/worn out brakes. If the ABS senses ANY wheel lockup, you will get the ABS pump buzz and dropping pedal. My 94 SE does this sometimes (especially after a moist or cold "dewey" night) if one wheel loses a bit of grip on loose dirt or gravel when braking. If you have rear drum brakes and the linings and drums check out OK, I would sand down the rear shoes a bit, and scuff up the drums as well.

This is where I would start, but knowing that you have a "clicking" sound on your LF bearing when unloaded, you may have a bad (new) bearing sending false signals to the ABS computer.

[pappyl]

Update

Replace BOTH bearings on front
- Left - clicking sounds GONE (3 weeks old = warranty)
- Right - Howling is GONE (bloody thing was only 8 months old= warranty)

Wiring on both checked - both connections look good.

ABS is STILL kicking on very slow speed braking.

I am getting some noise (squealing on rear drums). I'll check the rear drums too.
I need to check out the wiring from the front up as well. A poor connection can be causing this.

Not giving up on this....

[2000Silverbullet]

The 94 was doing exactly what yours is doing. Diagnosed as the Electronic Brake Control Module. We just pulled the fuses and it's non ABS now. The dealer wanted $1,500 for the new part.

[pappyl]

Well My wife likes the traction control... so...

Seems after some more web searching "low speed abs engaging" this problem is NOT so unusual.

This problem started at/near when I replaced the left bearing. I think I have a wiring issue.
I also think I need to check the harness up to the control module. I think its under the windshield washer bottle - gotta check it out.

I found a post where the wiring under the plastic covering was known to corrode. All worth checking....

Old car. Pain in the butt.... I do not like wiring in Pontiacs. Has similar bunch of problems with my brother's grand am. Wiring Wiring Wiring,,,,

[2000Silverbullet]

Keep updating this post. If you find your problem, you might be able to solve mine.

Yes the wiring in these cars is problematic. In efforts to save weight, they reduced the gauge size of all the control wiring and reduced the voltage to 5v. Corrosion and fatigue breakage over time is inevitable.

[pappyl]

Will do... Been busy over the weekend... As soon as I get some time.
Will post the results....

One other thing... going to do a ohmeter test on each bearing speed sensor
They're also supposed to be consistent + wiring

[LeSabre in Buffalo]

Mine did the same thing with a bad wheel bearing before it went bad. It was a cheap replacement hub that did it. I replaced both with more expensive hubs, and the problem didn't come back (yet). It's been 8 months for one, and 2 months for the other.

[MeLLoCeLLo]

Any luck on this ABS issue?

I've had this issue since i bought the car 4 years ago. I had to replaced the left/ front hub a year after i bought it; problem still was present.

I pulled the fuse about 2 years ago and driven like this ever since, but i've been wanting to fix it ever since i spun out on a bridge this past winter in Chicago (no ABS to keep me straight). I cant imagine the ABS module failing at only 61,000 miles.

Actually, i just had my brakes done all around and didn't think about plugging in the fuse again, I'll check this later on tonight.

There's no way i'm spending 1500 bucks on a module. Any other ideas? Possible harness under washer fluid tank?

[LeSabre in Buffalo]

EBCM is easy to get at, and pretty easy to replace on this generation. A junkyard one should be just fine.

[MeLLoCeLLo]

Is it under the washer fluid tank? I kinda want to check the connections (online says it can be corroded).

[pappyl]

Changed the connector lines with junkyard ones (between bearing and inside of frame at engine compartment). No difference (talked with a gent from mufflerman - this is first culprit). The junkyard ones "could" be defective as well, but physically they look perfect.

Checked rear connections/lines as well.

Pulled fresh air intake, etc. to check wiring. No corrosion anywhere. Did not undo the large "rotate to disconnect" connection (what a mass of wires there).

I'm going to bring it in and get the "professionals" to give me a diagnostic on this one. This is a PITA.
ABS not as important as the traction control - to me anyways. So this is going to cost me a bit more for diagnostic.

[willwren]

80 to 100 bucks just to scan it, IF that even shows a problem.

FWIW, I had a very similar problem in the ZiLLA at WCBF last year. Master cylinder was sticking. No lights, bells, warnings. Just locking up the brakes. It actually happened on the track while racing.

The PMV is under the airbox. The EBCM is to the right of the gas pedal inside the car on the firewall. Both units are VERY expensive new. Wrecker parts for the PMV are hit or miss (been there, done that). The EBCM would be a safe bet from a wrecker.

Just don't count on it being anything an electrical/computer scan can see. It may be mechanical inside one of those components or in the MC.