98 chevy tahoe. When am braking the pedal drops and the abs feel like taking over. No codes came when ran thropugh the diagnostic machine. Was told by one mechanic need both wheel bearings. Although some one else says the brake booster, but, I don't hear any air hisssing. Truck has all original parts still.
Brake booster? Really? All that does is makes the pedal easier to push. New wheel bearings will likely solve the problem but false ABS activation is a real common problem on all GM vehicles. On the trucks it's often caused by rust buildup under the front wheel speed sensors. They're bolted onto the bearing assemblies and don't develop much of a signal to start with. Rust pushes them away from the tone ring so the signal they develop gets even weaker until the computer no longer recognizes it. Electrically there is no problem so no codes are set. The apparent loss of signal just makes it look like that wheel stopped rotating so the ABS kicks in.
Remove the front wheel speed sensors and clean the mating surfaces. You might have to remove the bearing assemblies to get them off. If you have to do that, never allow the vehicle weight to sit on them without that huge axle nut torqued to specs. Doing so will instantly make it noisy.