ABS Freakout

[TWITCH101]

catalytic converters???I guess you mean they get clogged? and what are symptoms of the abs pump going out?

 

[TWITCH101]

Went by autozone and they asked about a police edition caliper....I was like Wtf??? Is it a larger caliper or something? Anyone know if its any different or if it will bolt up?

 

[DCT]

catalytic converters???I guess you mean they get clogged? and what are symptoms of the abs pump going out?

Check Engine light.

 

[TWITCH101]

Ok so I was driving yesterday and hit a speed bump while applying the brakes and it caused my abs to go ape shit for about 2 seconds. I mean I could hear the pump going haywire and the brakes got very, very soft. Could this be my bearings are bad and this is causing my sensor to give a bad reading which is causing the abs to freak out?

 

[delta579]

Cheapest first. Check wheel sensor wires/connectors at both wheels. Replace wheel sensors. You should be able to hear/feel a bad wheel bearing when the truck is up and you spin the wheel.

 

[TWITCH101]

yea I had her up about 5k miles ago and couldn't feel anything but then again I dont think I know what a bad one feels like vs. a good one. but I need the resistance for the sensors so I can check them with a meter to know if they are good or not.

 

[delta579]

I don't know the resistance levels for the sensors. They are a magnetic pick-up sensor, no moving parts, similar to crank/camshaft sensor. It's highly improbable that both would go bad at the same time though. Check the resistance readings on both, it should be the same. If they are not, then go to your parts place, with your meter, and check the resistance on a new sensor. This should tell you if need a new sensor, and which one it is.
Wheel bearings ? Normally you will hear/feel a grinding/rubbing. Remove the tire and spin the rotor using the lugs. Metal transfers sound better than rubber. Use a stethoscope or length of fuel line(rubber or metal) against the bearing housing. Compare both right and left sides, there should be very little noise coming from the housing. Hope this helps.

 

[electro]

Measuring the wheel speed sensor using a mV scale while rotating the hub one revolution per second i believe is the correct way to check for a bad sensor.

The hub rotation will produce a mV. It should be 250mV or 350mV for a good one. I cant remember the correct number. I will check later.

This can prove difficult as a multi-meter with that scale is expensive.


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[Wake]

It could be as simple as a bad wheel speed sensor.

It wasn't on my Escalade but my previous SUV, a Trailblazer.

Stopping was fine until I was just about stopped and then the ABS would kick the pedal back at me. It's a weird feeling when your truck is fighting you on the brakes.

I hooked up a scan tool to the vehicle and saw the bad sensor on my right front wheel. It would intermittently drop out to zero MPH below 7-10 MPH, telling the ABS computer that a wheel had locked up and it would kick the ABS in.

Had it happen a second time about 3 years later (thanks crappy eBay wheel bearings) and ended up having to replace the bearing assembly as something was going on with the reluctor wheel inside that the sensor uses to determin speed.