Four problems related to suspension have been reported for the 1999 GMC Sierra 1500. The most recently reported issues are listed below.
The contact owns a 1999 GMC Sierra 1500. The contact stated that the vehicle made an abnormal grinding sound from the rear end after hitting a pothole. The vehicle was taken to the dealer where it was diagnosed that the rear differential was defective and needed to be replaced. The vehicle was repaired, but the failure recurred. The rear differential was replaced four times. The manufacturer was notified of the failure. The failure mileage was approximately 186,000.
Coming to a stop sign I applied the brakes and they completely failed without warning; no lights or indication failure was imminent. The pedal went to the floor with no resistance. Managed to turn onto a dirt shoulder and downshift to stop. Inspection revealed rusted through rear brake line. Although the dash brake warning light comes on while starting the truck, it goes off and gives no indication the brake fluid is low. While repairing the brake lines it was noticed the frame of the truck is extremely rusty and flaking. After wire-brushing by hand,the frame is showing cracks on both sides, under the cab, near the rear, right about where a crossmember is attached. This vehicle is no longer safe to drive. I am not impressed with gm's claim that this was a lighter, stronger frame on this truck. We have 2 older trucks with nowhere near this much rust and neither have cracked. The design allows too much crud to accumulate inside the lip of the frame where it is almost impossible to wash out.
Frame rotted,suspension rotted,front suspension lock totally rotted.
I have severe frame rust to the point where the frame has a crack halfway around it near the rear suspension. The factory mounted tow hitch literally broke completely off of the frame due to the amount of rust that was built up around the welds while I was towing my camper, luckily I had just made it home from a trip from camping when this occurred. I can literally peel off 1/8" thick pieces of rust at a time, the truck is no longer operable due to the safety aspect, I have never seen rust like this on any vehicle, even ones that have been around the ocean and salt, after reading many complaints about the same issues with these particular model and year trucks ranging from 1999-current I have decided to file a complaint, maybe if your administration gets enough of these complaints something can be done to correct the issue and hopefully gm will do something to compensate so many of their disappointed customers or better yet fix the issue, this will be the last gm truck I purchase due to their negligence and after reading 100's of complaints of the same issue gm doesn't seem to care they just give the run around just like when I have had problems with my vehicles in the past under warranty.