Brakes pulsating - 2008 Pontiac Grand Prix

run fault codes
pulsating brakes only occurs under heavy braking when the pulses come from the releasing of the brakes and the reapplication of the brakes by the ABS controller
what you write suggests warped discs and or brake pads worn out
the pulsations could also be from failing wheel bearings allowing the sensor head to touch the rotor on the hub
run the fault codes and have a professional brake specialist shop check the brakes

have you had your brakes looked at? Sounds like warped rotors.

your abs is actovating posably a bad tone ring or wheel speed sensor

you could try the abs pump itself try getting one from a breakers yard
hope this helps

It could be a warped rotor or an out-of-round drum but it might also be loose wheel bearings, a bent axle shaft or loose brake parts. Or you might just be feeling you ABS kicking in. If it is one of those parts and you need to replace it, consider looking online for used auto parts.

Inspect your brakes. Pulsating usually indicates an uneven component, most times a rotor or a drum... so when you go to fix it, count on buying more than just the pads this time.

This is due to uneven surface of Brake Disc. Possibly you have to change them for smooth brack

if the pulsating in the steering occurs while braking this is an indications that the rotors are out of round and need to be turned or replaced. if they are causing a pulsating while driving without braking it could be the calipers sticking.

your back brakes will be cooler than the front brakes as the majority of braking is done ith the front brakes even on four wheel disc brakes. hope this helps.

Even though you replaced the rotors, seems that you will still need to have them resurfaced. This assuming you are experiencing pulsation only when braking.
Hope this helps, Please remember to rate this answer.

That is just the ABS system at work. It is supposed to prevent your wheels from locking which often makes the brake pulsate, especially in wet weather or or snow or ice. The only way to really stop this is to disable to ABS by unplugging it and removing the fuse. This will make the ABS light appear in your dash, but your brakes will stop pulsating.