My brakes start grabbing like the anti-lock brakes are trying to take over, the low trac light comes on, abs light comes on, and the check engine light all come on, after the lights come on the brakes work fine, I am being told after the lights come on the abs system is turned off because there is a fault in the abs system, had the codes ran and first code says left front speed sensor error, second code says RF wheel sensor frequency error, any ideas?

SOURCE: Olds Alero 99 Left front hub assembly

It sounds more like it's the wheel speed sensor that is part of the hub/bearing assembly. Since you have had the hub replaced many times I would look for the electrical connectors for the wheel speed sensor as the problem. An easy no cost fix.

BTW...GM has issued a service bulletin for the hub/bearing kit that states NOT to use the old style nut that comes in some kits as it will cause premature bearing failure due to it's design and the high torque requirements. The correct shaft spindle nut part number to use is p/n 10289657 and is torqued to 178 nm. The GM bulletin number is 03-04-18-001.

SOURCE: abs/trac off/service vehicle soon lights come on intermittent

its probably a wheel speed sensor or " " harness. if you replace your hub assembly it will take care of the problem. a new hub will run you between $100-$130. its an easy fix if you have a little mechanical knowledge. i dont know what labor would cost but if you know how to change your brakes you can figur it out.

SOURCE: anti lock and trac off

the abs wiring is in wheel bearing . you could have a bad bearing . a shop with a scanner could tell you witch one is bad or has wiring problems. aleros wiring run down lower control arm to wheel bearing. on control arm the wires get cut inside plastic loom and you cant see it till you pull them out and look .once you fix problem the lights will go out on there own.

SOURCE: anti-lock light comes on and stays on

chech the front hub assimbily if bgoing bad will triger abs light had same probilm with mine

SOURCE: ABS, brake, trac control, service engine soon light came.

check the wiring harness, on both front wheels, it plugs into the wheel bearings, and runs along the lower control arm, sometimes it gets damaged