Both brake and abs lights are on. I've replaced both front wheel hubs, and checked all fuses.cant seem to locate the problem

check and test fuses and connections --check hub brakes and abs sensor for failure the sensor is incorporated into the hub so if hub failing can cause abs and traction control trouble lights

Have you checked GM, as well as repair shop data base
Bulletins for those brake issues?

Have you checked with professional scan tool in the
abs module for codes?

Who is replacing those parts & why?

Would seem more like an axle tone ring,wheel hub
tone wheel inside bearing hub,abs module needing to be reflashed
with an update or wheel speed sensors.

There are ABS wheel speed sensors on the front wheels behind the hubs. It is possible if the hub where replaced either the pick up ring mounted to the hub itself was not installed or might have purchase non abs hubs or they just did not switch the wheel speed pickup ring on the new hub. Another thing could be either the wheel speed sensors are mis adjusted or when they replaced the hubs they hung the spindle by the abs wire and either pulled it out of socket or messed up the wires internally. Here is a basic abs system http://www.ehow.com/how_8511860_diagnose-abs-brakes.html if you have any other questions please let me know. Also please leave good feedback.

Ok, there are sensors on your front wheel hubs. This could easily cause the abs light to turn on. The loud noise could easily be your wheel hub going bad. Easiest way to check, jack up the front of the truck, grab tire, shake back and forth and up and down. Same amout of play each way? You're wheel hub is bad.......

that sounds correct,
the ABS sensor is located in the front wheel bearing,So it's easier to change bering and hub assembly

check connector and sensors for damaged ,or disconnected wires if good have vehicle scanned some auto stores such as auto zone / advanced auto scan for free the trouble code will give u a place to start with ur abs disconnecting the battery wont reset the abs if a sensor is bad

I'd be checking the sensor (ABS) at that wheel, (right front) and adjusting rear brakes to proper clearance, as well as inspect them for proper operation with wheels off.

Ask your mechanic what specific codes he extracted from your vehicle's computer and repost.

RAVE says the following:
1) Release ABS Sensor harness grommet from inner wing valance and disconnect multi plug.
2) Raise front of vehicle.
3) Remove road wheel.
4) Pull ABS Sensor harness through aperture into wheel arch.
5) Release harness from brackets on inner wing valance, suspension turret and front hub.
6) Release stake from drive shaft nut
7) Remove drive shaft nut with assistance & discard.
8) Remove front brake disk (Remove calliper, pad holder, screw and tap to remove)
9) Remove 4 bolts securing wheel hub to steering knuckle.
10) Release wheel hub from steering knuckle then remove wheel hub and drive shaft assembly from axle. DO NOT REMOVE ABS SENSOR FROM HUB. HUB AND SENSOR ARE SUPPLIED AS AN ASSEMBLY.
11) Position the wheel hub and drive shaft on a press, place supports beneath the wheel studs and press the drive shaft from the wheel hub.
12) Remove drive shaft oil seal from axle casing.

Refit is mostly the reverse, you need to take care to lubricate things in the right places and put loctite on the drive shaft and locate the loom and torque everything right.

A common cause for an ABS light is a broken wire to one of the front wheel speed sensor, or the sensor itself is bad. The sensor is part of the hub/wheel bearing assembly. A problem in the ABS causes the traction control system to be dissabled, thus turning on that light.