Issue with SCC and/or AEB? Brakes seem engaged while driving

[chastehel75]

Hello all. After some searches for "AEB" and "brake hang up" I'm posting this.

I have a 2015 Genesis 3.8 H-Trac.

On several occasions recently, while driving, mainly at 40+mph, I feel a vibration that increases. One instance on the highway, with the SCC on, it got to the point where the steering wheel was shaking, the rear-view mirror was shaking, and I could smell hot brakes. I turned off the SCC and the issue went away. Three times since, I've felt the similar creep of vibration and have resorted to turning off the traction control, thus disabling the AEB. Today was the latest, again on the highway going out of town, no cruise, but after about 10 miles, the shaking increased, I turned off the traction control/AEB, and in a few miles things smoothed out. On the way back, after I started the car before I drove away, I turned off traction control/AEB and the ride home was fine - about 40 miles of highway driving.

I'm wondering if there isn't a problem with the autonomous emergency braking that is allowing the system to apply slight pressure to the brakes.

I think that at this point I've got a slightly warped rear rotor because of the issue.

I live in northeast Ohio - is it as stupid as I need to make sure I clean the front radar sensor off each time I drive?

 

[SuperKing]

Nah, if the radar was dirty, the system just won't work and it would tell you in your dash. There's no partially functioning AEB/SCC, it's either on or off. You probably have a seized caliper?

 

[Suburbazine]

What you're describing suggests that you have mismatching tires installed. One or more tires is too big/little and may be causing the stability control to flare the brakes in response to "measured" slippage. Normally you'd get a speed sensor error with so much mismatch but you may be just under the margin required to throw a code.

Are all the tires identical size, brand and installation date? On HTRACs you're supposed to replace as a full set if below half tread depth, not one at a time.

 

[chastehel75]

Thank you for the two replies, I appreciate them. I'm sorry for my tardy response.

The problem ended up being a poor pad installation. Possibly a flat-rate job from one dealer to another.

I didn't mention that when I bought the car from a dealer they touted it had new tires (I checked the date codes and they were all close and recent, plus they still had the little nubbies on them) and pads and rotors all the way around (they looked shiny and new!). I bought the car used from a Dodge dealer, and the carfax showed the work was done at the neighboring Hyundai/Genesis dealer.

I was afraid to get into for fear of knackering up a sensor or breaking something so I took it a small independant shop that I've used before. The mechanic discovered that when the pads were installed it's possible that none of the hardware was greased and that potentially the old hardware was re-used. He charged two hours to disassemble the front calipers and pads, knock the edges off the pads so they traveled easier, clean and grease the hardware, then reassemble it. 3,000+ miles since the work and not a problem.

That and an alignment (since they had it) and it's almost like driving a new car.