Which parts fail
Components named in complaints (seat frames, recliners, heated seats and seat tracks).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 1999 GMC Sierra owners, lightly cleaned up (personal details are redacted by NHTSA).
1-seat adjustment 2-seat will not lock in position-slides freely front to back 3-temporarily locked failed piece into usable position-cannot adjust to any other position due to failed plastic block. Researched complaints for 99 GMC Sierra truck and found 10 existing identical failures. These are complaints-566049, 758819, 855016, 862903, 877718, 10020665, 10022698, 10066125, 10074822. I am sure there will be additional complaints under "mirror" vehicles such as Chevrolet and cadilac and other years. I have identified the piece as a plastic block approximately 1 inch wide by 2.5 inches long with a lever, spring and pin assembly. The "u" portion of this block fails causing the seat to slide freely creating a severe safety issue. This is clearly an unsafe and poor design. …
Son was driving 99 GMC Sierra truck on I-20 in arlington, tx Monday, May 26th when he braked to slow and the front driver seat suddenly lurched forward throwing him into the steering wheel causing him to lose control of the truck. He regained control of the vehicle but was almost rear ended by vehicle. Son and fiancee were unhurt and no damage was done. When they were able to pull over and investigate, the front driver seat would not lock in place. It would move forward and backward without locking into place. Son had to brace his foot against the dash to hold seat in place in able to drive the vehicle home. Serious injury could have been the result if control of the vehicle had been lost. Feel this is a manufacturers defect and serious injury could result if this happened to others or myself since I drive the same identical vehicle.
I have a 1999 GMC Sierra extended cad truck the drivers seat adjustment made of plastic when it breaks the seat will not lock. The seat belt is attached to the seat so in the event of an accident all that is holding is flimsy plastic. I checked all the salvage yards in my area they said every truck that they have that has wrecked the plastic slide is broken. To me, my wife and my life are worth more than this plastic piece. GM needs to recall and either fix this piece with metal or different seat tracks. My seat broke just adjusting it.
While approaching a stop sign at approximately 20 MPH, the driver side seat adjustment broke free and the seat slid forward. Because of the anchorage of the seat belt being the seat itself, nothing held me back from contact with the steering wheel. Fortunately this happened at a low rate of speed. I am in the process of seeking reimbursement for repair cost in the amount of $513.11 from GM who would not cover the repair because the vehicle is out of warranty.
The drivers seat adjuster fails to hold the seat from sliding back and forth. I have manual bucket seats and have been told by GMC that there is no records of failures. This has been repaired 5 times by replacing the seat adjuster, all under warranty thus far, but I am concerned that this is a safety issue since if it fails while driving, it allows the driver to be moved forward when brakes are applied.
Operated release lever on drivers seat to gain enterance to rear seat area. Hen seat back was returned to up right position, seat would not lock in any position. Drove to local garage, very dangerious. Mechanic advise seat track was broken. Ordered new track from GM, cost $164+tax + labor to install. Saved old track for NHTSA inspection. Seat tracks is a safety item. Now to convince GM.
Dt: consumer states when he parked his vehicle he raised the seat. When he got back in the truck the seat kept moving back and forth. The seat will not stop going back and forth. The dealership replaced the track and the parts to the seat. The repairs were made at the owners expense. The seat track was repalced. Updated 12/07/05.
Dt*: the contact stated while stopping the vehicle, both front seats move forward/backwards a quarter of an inch. The dealership determined the entire seat assembly needs to be replaced. Updated 5/10/2006 - the power seat track on both front seats were loose.
There is a bar that is at the base of the front drivers seat which comes out at the console. The bar cut straight through the seat. The bar is very sharp, and the consumer was badly cut by the bar .
I was having trouble moving the drivers front seat forward or backwards, I left it in the foward position as I was driving along a city street ,I came up to a light and the seat anchorage became broken causing me to strick the steering wheel.I feel that if I had been going faster then 25mph I would have gotten hurt worse. I had a factory defect on the front seat belts,which I had taken to the dealer ,I was adviced that the parts were not in and had to be ordered. This was back in November or so to the best of my recllaction. 2-28-2001 I called the GMC customer assistance office spoke with a GMC representative and declare my problem , I wanted this deficiency to be covered under warranty,and I was adviced that it was not. …
Seat complaints in other Sierra years
Frequently asked questions
How common are seat problems on the 1999 GMC Sierra?
NHTSA has 23 complaints about the seats of the 1999 GMC Sierra, 4% of the model year's 600 complaints. The component named most often is front assembly › recliner (2 mentions).
Is there a recall for 1999 GMC Sierra seat problems?
No. NHTSA lists no seats recall for the 1999 GMC Sierra, though it has 5 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 1999 GMC Sierra seat problems start?
Half of the complaints with a recorded mileage happened before about 68,000 miles.
Is it dangerous?
Owners linked 0 crashes, 0 fires and 1 injury to seats problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.