My driveway is on a decent incline and I notice it most often on my driveway; never when on the road, even going down a mountain. It seems to happen almost only when I am parked, then immediately drive down a driveway that has an incline.

I back out of my garage, brake, and its fine. Turn toward the bottom of my driveway and start driving down. Halfway down, I will apply the brakes and they feel like they press further down than usual and make this ZZZZZ noise, and it feels like its not doing much to stop the car. It almost feels like when you stop on ice or snow and your ABS kicks in, but I am not sure its that. It only happens that once. If I let go of the brakes, coast the rest of the way and then press them again, everything seems to be fine.

What is the first thing I should look for? Without taking my wheels off, it looks like I still have brake pads left (felt like it with what I could tell).

The rotor feels smooth, but the area that the brake pad touches is slightly worn down compared to the rest, maybe 1mm or so. This appears so for all 4 rotors.

 

Happens immediately and never happens again? I think it's the car doing the ABS diagnostics. I think I've heard this once or twice. Try backing out and stopping once or twice before getting all the way down. See what happens

 

I agree with Jeff. Your car will do the ABS check when it reaches ~ 10 MPH and if you are pressing on the brakes at the time you will feel vibration in the pedal. To me it sounds like running over a grate briefly when it happens. Totally normal.

 

I can probably better describe the behavior now that I re read what I actually wrote.

If I start at the top of my driveway and immediately lightly press the brakes, I won't hear/feel this grinding/pulsing noise or feel it in my pedal.

If I drive any distance and then just press the brakes regularly, I will get the described behavior. If I press the brakes near the top, feel it pulse/grind and then let go, I can drive to the bottom, press the brakes again and NOT feel that same behavior happen.

A few weeks ago I drove to a friends house, got out for a few minutes, then drove down her driveway and it seemed to pulse again.

Now, say I have been driving on the road and stop at the top of a steep hill, then need to brake when going down it. I won't get that pulsing/grinding noise.

 

That is interesting. My 350z, or any other car i've driven has never done this before. So this is normal? I never notice any lights on my dash going on when I brake going down my driveway. Is there an ABS notification indicator/light on the dash that goes off when it does the check?

 

No lights will come on. The G is the first car I've owned that makes an audible noise. It happens every time the car is started though. Weird I know.

 

Odd that it only happens on an incline though. I can be parked in a parking lot all day, get in start it up and slowly drive away, apply the brakes and not experience it. No pulse, no grinding, no noise at all.

I am not asking further questions out of distrust of what you are saying. I am just curious why it happens on an incline and not a flat surface.