Just bought my daughter an 02 Tahoe. Nice vehicle but its been sitting for about 4 years. Changed fluids, checked frame, new tires. Still needs a few things but drives good. Problem is, every once in a while, especially if you lock up the brakes you get a groan and the brake pedal locks up and you have to fight it to get it stopped. Is this the ABS? If so, can I just pull the fuse to disable it? if your not getting the groan, it stops really nice. Brakes and rotors looked rusty but brakes had about half of a pad so the guy inspecting it said to drive it and that should work itself off. I dont want her on the interstate, have to slam on the brakes and not be able to stop because it pulls this, Its like, when it kicks in, something is pushing against your foot while its on the brake pedal.

 

You can try pulling the ABS fuse to see if that does anything. I think you'd normally get a brake light if the ABS module fails or has an issue.

I would make sure the calipers aren't seizing. Remove, inspect and lubricate the slide pins on all 4 brakes.

 

To answer your question, yes the pulsating in the pedal is the ABS activating. If you dont have a light, The system should be working properly so to speak. Also verify all the tire pressures are the same as this can also effect the braking System.

You could have performance issues with the brakes though. I would recommend flushing the fluid as well if was sitting for 4 years. Brake fluid is Hydroscopic. Meaning it will absorb water. Checking the slide pins on the calipers and lubricating them is also a good idea as mentioned above. Sitting for that long they could dry out and develop corrosion.

Find a old side road where you can safely test them and will not be effected by traffic. Drive up to 40 MPH or so and apply the brakes till it slows to about 20 MPH then back up to 40 and brake to 20 and then 1 more time. Then bring it to a gradual stop. Then put it into reverse and try to go backwards to about 20 MPH and apply the breaks down to about 10-5 MPH and then up in speed and break back down just like before 3 times in a row. When Going backwards it should gradually feel tighter each time.

This should clear most of all the crap off of the rotor and pad surface as well as make sure everything is in adjustment and functioning properly.

 

It's going to need wheel bearings sooner than later. A vehicle sitting for 4 years plus the problem he described is a sign one or both of the bearings need replacing in my opinion.

If one of the wheel speed sensors drops out to zero or goes way lower than the other wheels, it will kick the ABS in. A scan tool could watch each wheel and you'd be able to tell right away which one it is.