We have a 2009 Suburban that we just cant figure out what is going on. We live in Colorado so this only seems to happen coming downhill, and only sometimes. It feels as if the right rear wheel shimmy's but it does only happen sometimes, and can be the first time the brakes are hit so they aren't hot. Our first thought was a warped rotor but it is odd that it doesn't always happen. I heard it might be a faulty ABS Sensor? Anyone know anything about that? I am not getting any codes-brakes and tire look good, less than 100K on the vehicle.

 

im assuming its when you are braking that it happens? It could be the abs activating when it shouldn't from a bad abs/speed sensor. The only way to know for sure would be having the ability to graph the sensor data while it was happening

 

Is this something that can just be replaced to see if it fixes the problem or is it horribly expensive to do so.
Because this happens only when going downhill, is it possible that the weight of the vehicle being shifted may have something to do with it? (grasping at straws here) She has had to be on the brakes hard a few times in Denver and nothing shook, coming down I-70 the rear shakes like it is on rumble strips.

 

pull the abs fuse; if the problem goes away, its abs related.