ABS light and Wylie Coyote

[samss]

My daughters 2006 Xterra (2WD) occasionally makes a weird noise, like a spring loaded trap that Wylie Coyote has tripped. The ABS light comes on and goes off with the next key cycle. This only happens at slow speeds, coming to a stop and straight or turning.
She hasn't noticed the brakes pulsating or spongy.
I'm hoping to get a look at it tomorrow. I'll check for wheel bearing play and rotor, pad condition.
Any mechanical advise from the GJ knowledge vault?
TIA

 

[samss]

Update
The weird noise was the ABS activating. I got her to drive on a grassy area so she could slam on the brakes. The steering, suspension, brakes and tires all look good.
I'm still wondering why the ABS would activate at such a slow speed on dry pavement. Of course, it wouldn't act up for me.

 

[Wrench97]

Usually wheel bearing getting loose or the sensor is rust jacked up away from the ring.
This is one you really need a scan tool for to see which one is acting up before firing the parts cannon.

 

[Mick56]

If you stop at an Auto Parts Store, won't they check it for codes for free?

 

[CraigStu]

Usually wheel bearing getting loose or the sensor is rust jacked up away from the ring.
This is one you really need a scan tool for to see which one is acting up before firing the parts cannon.

Back when I was a Lexus tech we had one Lexus model that had that exact problem w/ the rear sensors. The cure was destroy the sensor to remove it because the hole it was mounted in had gotten all rusted and it had moved some but then locked up. Another model had a problem where the toothed ring was a piece of cast iron that pressed in place around the CV joint. The surface of the joint would rust so it essentially expanded which put a crack in the ring. So all the teeth were spaced the same except those on either side of the crack. Both cars seemed to discover the problem when the ABS was going through it's self check which happened in the first 100 yards or so. We never got a real explanation why it would do a weird buzz sound during the self check but then worked fine for the rest of each trip.

 

[theoldwizard1]

I'm still wondering why the ABS would activate at such a slow speed on dry pavement. Of course, it wouldn't act up for me.

Different vehicle entirely. The wheel speed sensors on the front were severely rusted giving intermittent reading at low speeds. Replaced both and the problem was solved.

 

[Wrench97]

If you stop at an Auto Parts Store, won't they check it for codes for free?

Codes are only part of the story and with auto parts stores ammo for the parts cannon, with this you need to see the data graph of the wheel speeds looking for the one with a small glitch while driving/stopping.

 

[Wrench97]

Back when I was a Lexus tech we had one Lexus model that had that exact problem w/ the rear sensors. The cure was destroy the sensor to remove it because the hole it was mounted in had gotten all rusted and it had moved some but then locked up. Another model had a problem where the toothed ring was a piece of cast iron that pressed in place around the CV joint. The surface of the joint would rust so it essentially expanded which put a crack in the ring. So all the teeth were spaced the same except those on either side of the crack. Both cars seemed to discover the problem when the ABS was going through it's self check which happened in the first 100 yards or so. We never got a real explanation why it would do a weird buzz sound during the self check but then worked fine for the rest of each trip.

Cracked alloy rings on Toyota axles are quite common usually they cause a constant rather then intermittent issue, increased air gap from rust jacking is more intermittent and since I believe this the have the tone rings inside the sealed wheel bearing hubs makes the rings less suspect.

 

[samss]

Looks like I'll be taking it to my mechanic next week.
Wrench97
"since I believe this the have the tone rings inside the sealed wheel bearing hubs makes the rings less suspect. "


Thanks for the replies and info. I'll update when it gets back from the shop.

 

[vavet]

I had a problem with a 2003 Ranger. The toothed ring on the front rotor was pressed on too far when it was assembled so the sensor never saw it. The abs activated whenever I used the brakes and the steering kicked to the side opposite of the problem rotor because the abs was releasing pressure on that caliper.
All this happened right after I’d installed new rotors and pads, so I knew it was something related to that...but it took me a little while to figure it out.
Sounds like your situation could be similar.

 

[Wrench97]

Looks like I'll be taking it to my mechanic next week.
Wrench97
"since I believe this the have the tone rings inside the sealed wheel bearing hubs makes the rings less suspect. "


Thanks for the replies and info. I'll update when it gets back from the shop.

Here is a decent video of what rust jacking does to the sensors>

 

[jkeyser14]

The ABS sensors don't start working until ~5mph on most cars. Once the car hits 5mph the ABS system checks the sensors it is probably getting a bad reading and kicking on. Could be a failed sensor or a rusted/damaged tone ring.