Three problems related to front suspension hub have been reported for the 1999 GMC Sierra. The most recently reported issues are listed below.
Consumer states: anti-lock brake system, when applying it makes weird noise, and has to push brakes to the floor. Had to do 4 times, was under 5 mph and pedal kicked back, and it grabbed. Just got abs serviced and new fuse put in. Had to take out fuse for the brakes to work properly. Could hear whinnying noise before taking out the fuse, and light came on at the same time. Dealer hooked up vehicle to diagnostic machine, replaced right front hub and bearing assembly, and still having the same problem.
At slow speeds there is a clanking sound in the brakes, and can be felt in the brake pedal on the consumer's foot. This has been a problem since 2002. The vehicle has been in the repair shop 3 times for the same problem. The first time, the vehicle was involved in an accident in the parking lot. The owner was driving 5 mph or less and had no brake control, and the pedal was working against the driver. The owner took the vehicle back to the shop 2 more times for the same problem. Gm, the manufacturer came and inspected the truck. Gm would not allow the truck to be fixed by the dealership until they inspected it. The dealerships report stated that they replaced the right front hub bearing after testing and the found bearing caused unwanted abs operation during slow speeds. There were no injuries in the crash.
Abs brakes fail when you apply brakes when there is a bump in the road. I have had 14 failures in 2095 miles. The brake pedal drops down slightly and becomes solid, you can not push down anymore and the vehicle glides to a slow stop. It will not stop in an emergency in this case. The problem seems to be in the suspension and the abs brakes. The vehicle vibrates and does not recover fast when you go over a slight bump in the road. At highway speed the whole vehicle and steering wheel vibrates. The plastic hub nuts always come loose when driving.