Help with ABS Sensor
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Help with ABS Sensor
STFA and found that a potential cause for my brakes to pulsate while stopping is a dirty ABS sensor. Been searching the archives to see where the ABS Sensor is located exactly, but the post I found is old and the pics are red x's.
Does anyone have a picture? Is this a relatively easy DIY?
I have a 1999.5 A4 1.8T quattro with 84,000 miles (I know, I don't drive much). The ABS light is not On. Just today, everytime I step on the brake pedal, it slowly pulsates back against my foot. As the car slows, the pulsating slows.
Any other causes? Warped rotors?
Thanks for any help.<ul><li><a href="https://forums.audiworld.com/a4/msgs/2133484.phtml">https://forums.audiworld.com/a4/msgs/2133484.phtml</a</li></ul>
Does anyone have a picture? Is this a relatively easy DIY?
I have a 1999.5 A4 1.8T quattro with 84,000 miles (I know, I don't drive much). The ABS light is not On. Just today, everytime I step on the brake pedal, it slowly pulsates back against my foot. As the car slows, the pulsating slows.
Any other causes? Warped rotors?
Thanks for any help.<ul><li><a href="https://forums.audiworld.com/a4/msgs/2133484.phtml">https://forums.audiworld.com/a4/msgs/2133484.phtml</a</li></ul>
AudiWorld Super User
Joined: Aug 2005
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From: beside the Great Salty Wetspot
follow the wire....
seriously, it's at the end of one of the wires that run to your wheel hub.
the front wheel will have 2 wires: brake pad wear sensor and the ABS sensor.
rear wheels just have a wire to the ABS sensor.
hope you're savvy enough not to confuse it with the brake hydraulic line or the parking brake cable.
rotate the sensor GETNLY with a pair of channel lock pliers while pulling it out. If you're lucky you'll get it out without destroying it. sometimes they get rusted in there pretty badly.
when you get it out, spray carb cleaner and compressed air down the hole while you roate the hub. clean off the sensor itself, too.
the front wheel will have 2 wires: brake pad wear sensor and the ABS sensor.
rear wheels just have a wire to the ABS sensor.
hope you're savvy enough not to confuse it with the brake hydraulic line or the parking brake cable.
rotate the sensor GETNLY with a pair of channel lock pliers while pulling it out. If you're lucky you'll get it out without destroying it. sometimes they get rusted in there pretty badly.
when you get it out, spray carb cleaner and compressed air down the hole while you roate the hub. clean off the sensor itself, too.
AudiWorld Super User
Joined: Aug 2005
Posts: 4,904
Likes: 2
From: beside the Great Salty Wetspot
so describe more fully the pulsations you're feeling...
You'd feel the ABS pump pulses at a rate of 4 or 4 per second...or more, and it wouldn't vary with speed.
I'd want to look closely at the bolts holding the brake calipers on the hub, the lug nuts, and front suspension parts before messing with the ABS sensors.
I'd want to look closely at the bolts holding the brake calipers on the hub, the lug nuts, and front suspension parts before messing with the ABS sensors.
Thread Starter
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Re: so describe more fully the pulsations you're feeling...
No, the brake pedal does not pulsate like when the ABS activates normally. The pulsating varies with speed, going at 25 MPH would pulsate almost 2 per second, as the car slows, the pulsating slows to about one per second around 5 to 10 MPH until stop. So the car does not slow smoothly. And it sounds like the pads are worn down but when I look at the pads, they look fine.
Just today, I noticed the brake pedal was stiffer just after I started up the car. Also, I'm hearing a sound, almost like metal scraping or brushing up against something but in pulses, again varying with speed.
Appreciate the help, what are your thoughts? Sounds like it's time to visit the shop.
Just today, I noticed the brake pedal was stiffer just after I started up the car. Also, I'm hearing a sound, almost like metal scraping or brushing up against something but in pulses, again varying with speed.
Appreciate the help, what are your thoughts? Sounds like it's time to visit the shop.
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