Brake pedal vibrates then warning lights come on

[Squiggy]

Occasionally when I am driving I notice feedback from the brake pedal. Feels like a short 'vibration' or 'grinding' under my foot. Then the warning lights come on; Brake, ABS, Traction Control. Usually the lights stay on until I restart the car. The brakes seem fine, although I have not tested the traction control on wet roads. This all began several months ago before I replaced the brake pads and rotors. Thought that might help, but the problem has persisted. Sometimes the warning lights come on when I start the car, but usually not. Curious what you guys think it might be. Thanks

[andrewwynn]

It's the symptom of a problem wss (wheel speed sensor).

This can happen when there's enough rust on the end of the sensor or if the sensor is loose


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[Clavurion]

Yep. False ABS activation because of wrong wheel speed information from one wheel compared to others. Start with fault codes and with diagnostics check the live data from wheels so they are showing the same while driving straight.

[andrewwynn]

More feedback; you mentioned after rotor work. If you had any rotors that were stuck on and needed a little help with a hammer to remove that's a likely culprit.

I killed a was when I changed a bearing when I used a slide hammer to remove the hub and left the wss installed.

[Squiggy]

Originally Posted by andrewwynn

More feedback; you mentioned after rotor work. If you had any rotors that were stuck on and needed a little help with a hammer to remove that's a likely culprit.

I killed a was when I changed a bearing when I used a slide hammer to remove the hub and left the wss installed.

Thanks for the feedback! Will check the wheel speed sensors. Problem presented before (and after) the brake job.

[andrewwynn]

In my case I've seen this happen twice:.

Once when my wss worked loose becusse the bolt head snapped off during a bearing job and ever since it was friction fit with some wraps of Teflon. That worked perfectly until summer when the knuckle got larger due to ambient temp. It just needed another wrap or two of Teflon but took me about two weeks to get to it and twice I had to climb under the car add push the sensor back into place.

The other time, enough rust was on the magnetic tip of the sensor I pulled it, cleaned it and it fixed.

I also did break one sensor by slide hammer too close but I think that one showed an actual error.

Hopefully you can find your faulty sensor. The best way is to graph the speed and wait fora glitch. It's very difficult to see in the numeric display unless it's very obviously dead.

In the two times I had malfunction I had the same symptom.

Just about to come to a stop apparently one wheel indicated zero speed as if sliding on ice so abs kicked in to let it roll. After 5-6 jittery stops it gives up trying and disables abs for that drive cycle.

Sound familiar?

[Squiggy]

Originally Posted by andrewwynn

Just about to come to a stop apparently one wheel indicated zero speed as if sliding on ice so abs kicked in to let it roll. After 5-6 jittery stops it gives up trying and disables abs for that drive cycle.

Sound familiar?

Thanks for the tips. Mine does this... if the idiot lights come on when I start the car I notice no negative effects while driving (but have not tested the ABS or traction control on a slippery road yet). If the idiot lights do not come on when I start the car, while I am driving sometimes the lights come on even though I did not press the brake pedal. But now and then if the idiot lights did not come on when I start the car... out while driving I might press the brake pedal and I will get the 'grinding' feedback in the brake pedal, then the idiot lights will come on. Sometimes the grinding feeling in the brake pedal is coupled with a small sound like.. BRRRrrttt