When pressing down on the brake pedal it pushes back against my foot

Tiny
SNOOPY1989
  • MEMBER
  • 1997 GMC JIMMY
  • 4WD
  • AUTOMATIC
  • 15,000 MILES
Every time I try to apply the brakes it works then the pedal pushes back on my foot.
Saturday, December 17th, 2016 AT 8:24 AM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 12,972 POSTS
Very common. What is happening is that the ABS is activating and pushing back. The fix is not real hard but it can be a PIA if you are in the rust belt.
Basically the ABS sensor goes into a hole in the wheel hub to sense the speed each front wheel is turning. If the ABS unit sees a certain speed difference between any of the sensors (two in front one in the rear) it thinks a wheel or more is sliding and tries to pulse the brakes on the other wheels so the speeds all match again.

This can point the way but you will not need to replace the sensors, just get them out and back in, if you are careful

https://www.2carpros.com/articles/how-to-replace-an-abs-wheel-speed-sensor

Unfortunately, rust starts between the sensor and the hub and actually pushes the sensor out of the hole enough that it now starts to send a different speed signal to the ABS module. This makes the ABS apply more and more as the rust gets thicker. It will not turn on the ABS light because the module does not see something like a broken wire or a short.
To repair it is not hard. Jack up and support the front end. Remove the tires. Unbolt the caliper and remove the brake rotor (gives you extra room). You will see the sensor with the wire going to it and the bolts that hold it in the hub. The hard part is usually getting those out without breaking them. Clean around the sensor and be very careful with the wires., remove the bolts and gently pull the sensor out of the hub. Take a piece of towel, shop rag, cork and plug that hole with something that you can remove when finished before going any farther. Now use a scraper, sandpaper, Scotchbrite wheel (whatever you have) and clean off the rust all around the hole, do not remove the metal just the rust. Once done clean the sensor tip and remove the plug from the hole. Apply a bit of grease/silicone paste to the area that rusted and the o-ring on the sensor. Slide the sensor back into the hole. Install the bolts. Install the rotor and caliper and tire. Repeat for the other side (do both or the speeds will not match and you will end up doing it anyway). One thing I like to do once I get the sensors in is to coat the area around them with a thin coat of RTV silicone to seal the area from more moisture and rust. I have only had one time that the rear sensor had any issues when it came to this problem.
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Sunday, December 18th, 2016 AT 12:22 AM
Tiny
GIUGGIOLA
  • MEMBER
  • 0 POST
Thank you for the fix.
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Saturday, February 1st, 2020 AT 11:53 AM
Tiny
STEVE W.
  • MECHANIC
  • 12,972 POSTS
You are welcome.
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Saturday, February 1st, 2020 AT 3:20 PM

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