1999 GMC Sierra 1500 Problems

What owners report

Owners of this model year most often report brake problems, and the dominant story is rusty steel brake lines that burst and leave the pedal on the floor. These reports span a wide mileage range, from very low-mileage trucks to ones past 200,000 miles, and many owners say more than one line failed or that all lines were replaced at once. Secondary themes are corrosion of the frame and underbody, driver's seat latches that let the seat slide, and a handful of steering complaints.

1. 1
   Brakes

   Rusted brake lines bursting, pedal to the floor

   • 65 complaints (41%)
   • median 123,000 mi at 12.1 yrs old (59 state mileage)
   • 5 mention a crash, fire or injury
   • owner-quoted repair $1,000 (median of 11 quotes)
   • filed 2006–2019

   Owners describe pressing the brake and having the pedal drop all the way down, sometimes hearing a pop, with brake fluid then visible on the ground or dripping from under the driver's side. Inspections typically find a hard steel line corroded through, and repairs are often quoted as replacing several lines or all of them at once because the others look similar. Complaints describe stopping with the parking brake or by downshifting, and in some cases a low-speed collision; dealers and shops generally replaced the corroded lines rather than offering another remedy. Reported from as little as a few thousand miles up to well past 200,000, with many in the 60,000-160,000 range and often in vehicles used in road-salt areas.

   1 related service bulletin

   What to check: Have a shop inspect every hard brake line, especially where they run along the frame and above the rear axle, and ask whether any lines have been replaced. A 2014 bulletin notes pre-formed brake pipe kits are available for service.

   2 excerpts from owner complaints in NHTSA records

   “On april 15 2010, as I was bringing my vehicle to a stop, the brake pedal traveled all the way to the floor. When I got under the vehicle to examine it I saw the rear right brake line was leaking brake fluid badly due to a break in the metal brake line. Again on 2/27/2011, I was stopping my vehicle at a stop sign and the same thing happened at a low speed. Only this time it was a front right brake line. …”

   NHTSA complaint #10388428, filed 2011-03, 101,166 miles

   “1999 Gmc sierra, two cars infront turning left, went to apply brakes and pedal went to floor, no brakes. Ended up crashing into the car in front of me, which in turn hit the car turning. As I was making sure no one was hurt, I noticed that my truck was leaking brake fluid all over the road.”

   NHTSA complaint #10414035, filed 2011-07, 70,000 miles
2. 2
   Brakes

   ABS pump runs on / unwanted ABS activation

   • 18 complaints (11%)
   • median 50,500 mi at 5.8 yrs old (12 state mileage)
   • 1 mention a crash, fire or injury
   • filed 2000–2016

   Some owners report a humming noise that continues after the engine is shut off, traced to the ABS brake control module or pump, with the fix being to pull the fuse until repairs are made. Others describe the ABS engaging during slow, gentle stops with a grinding or clacking noise and longer stopping distance, sometimes without any warning light. Complaints say dealers confirmed the module or valve body as the source in some cases. Reported anywhere from roughly 24,000 to 130,000 miles, typically during low-speed braking.

   What to check: Listen for the ABS pump running with the key off and watch for the ABS light; on a test drive, note any ABS chatter or grinding during gentle low-speed stops.

   2 excerpts from owner complaints in NHTSA records

   “Brake failure due to malfunction of anti-lock brake system. Caused vehicle to coast through a red light at a busy intersection. Brake pedal went to the floor with no stopping capability. Anti-lock brake light on dash came on and stayed on. This has occurred on three seperate ocassions over the last three years.”

   NHTSA complaint #10119447, filed 2005-05, 24,330 miles

   “The ABS brake light was illuminated at all times. The consumer heard a humming sound coming from under the vehicle. The ABS module was disconnected because the module continued to run although vehicle was turned off. If the module was left connected it could drain the battery and possibly damage other systems. The dealer and manufacturer were informed of the problem. The ABS module has not been repaired due to the cost of the repair.”

   NHTSA complaint #10044789, filed 2003-11, 36,000 miles
3. 3
   Body and structure

   Frame and underbody rust-through

   Mentioned in 7 of 60 sampled complaints

   Owners report heavy corrosion of the frame, cross members and the tube that carries the rear shock mount, sometimes found only when the bed is removed for other work. In some complaints the frame was described as cracked or rusted through behind the cab, and owners say dealers inspected and declined repairs. Several mention related corrosion of fuel lines, transmission cooling lines and parking brake hardware found at the same time. Mostly reported on trucks with 100,000 miles or more, often in states that use road salt.

   2 related service bulletins

   What to check: Get underneath and inspect the frame rails, cross members and rear shock mounts for flaking or holes, and check the fuel and transmission cooler lines at the same time. Bulletins from 2014 describe guidance on underbody corrosion.

   2 excerpts from owner complaints in NHTSA records

   “I have a 1999 Gmc SIERRA 1500 z71 with 107000 on it a frame cracked under passengers door and at rear shock mount call GM told me to bring it to a dealer for a frame inspection told me frame is rotted nothing they would do I think it's a safety issue shouldn't rot out had a 1997 chevy 1500 never any rust on that truck it had 245000 miles when I sold it .if you need pictures of the rot on my 1999 Gmc sierra I will get”

   NHTSA complaint #11032280, filed 2017-10, 107,000 miles

   “Frame and cross members corrosion found when having cab rocker panels replaced and prep-repaint cab. Body shop called ask me to stop by have a look and that they had removed the bed. I was shocked at the cross member tube that rear shock is mounted to is almost corroded completely around over exaust muffler. Shop owner informed me he did not have ability to replace cross member. I am also concerned about the amount of corrosion over all frame-structure. We bought truck new, 50% of its time was parked under car port. …”

   NHTSA complaint #10723601, filed 2015-06, 243,000 miles
4. 4
   Seats

   Driver's seat slides or latch breaks

   • 9 complaints (6%)
   • median 56,000 mi at 10.8 yrs old (9 state mileage, few)
   • filed 2004–2016

   Owners describe the driver's seat sliding forward and backward while driving, sometimes close to two inches, after the latch or the rivets holding the seat to the track broke. Complaints mention the seat frame breaking as well, and that the movement can happen during braking or acceleration. Some owners say the dealer or manufacturer declined to address it. Reported from very low mileage (under 5,000) up to about 80,000 miles.

   What to check: With the truck parked, push and pull the driver's seat firmly to check for play, and look at the latch and rivets where the seat attaches to the track.

   2 excerpts from owner complaints in NHTSA records

   “The seat latches that hold the seats in place which are made of plastic break and the seat slides back and forth (all the way back and all the way forward toward the steering wheel). The latches on my 1999 Gmc sierra pick up truck broke in 2000 when the truck only had about 3700 miles on it. Gmc corp. Has denied the problem and refuses to talk to me about fixing the problem. It is a really bad safety hazard since they could break at any time and would slam you forward if you step on the brakes and backward when you accelerate. …”

   NHTSA complaint #10445691, filed 2012-01, 3,700 miles

   “The consumer began to notice that the driver's seat was not stable when sitting in it. Upon closer inspection the consumer found that the rivets holding the seat to the track were broken off. The frames of the seat broke as well when the rivets broke off.”

   NHTSA complaint #10055774, filed 2004-03, 40,000 miles
5. 5
   Other or unknown

   Steering wander, pump noise or gear box wear

   Mentioned in 4 of 60 sampled complaints

   Complaints describe the steering wheel jerking or jumping during gradual turns, a power steering pump that became noisy and then failed, and a steering gear box worn enough that a right turn became difficult. In one report the owner notes a bypass kit was available for an actuator on the pump. In others the dealer replaced the gear box. Reported between about 70,000 and 147,000 miles, with intermittent symptoms in some cases.

   What to check: On a test drive, feel for any sudden assist or jump in the wheel through sweeping turns, and listen for whine from the pump; check for play in the steering gear box.

   2 excerpts from owner complaints in NHTSA records

   “When driving down the road when going around left curve the steering wheel jumps to the left and comes back. It does not happen all the time it has been going on for two years and know one can find the problem. This truck was built in 11/of 1998.”

   NHTSA complaint #10788620, filed 2015-11, 130,000 miles

   “The contact owns a 1999 Gmc SIERRA 1500. On june 19, 2007, the power steering pump failed. The power pump fluid was full at the time of failure. While driving, the power steering produced a very loud noise when the wheel was turned. The noise continued to intensify before the pump finally failed. The purchase date was unknown. The current and failure mileages were 70,000.”

   NHTSA complaint #10193690, filed 2007-06, 70,000 miles

Buying note. On a used example, the brake lines and frame corrosion are the two things worth inspecting closely before buying, ideally on a lift, and ask for records of any line replacements. Seat play and steering feel are quick checks on a test drive.

Summary written with AI from a sample of 60 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.