Rust or structural corrosion on the 1999 GMC Sierra 1500
Only 6 reports for this mode came with an odometer reading, which is too few for percentiles to mean anything. The page is here because someone linked to it; treat the figures as anecdotes, and see the full report for this year instead.
When rust or structural corrosion gets reported
There are 6 reports of rust or structural corrosion on the 1999 GMC Sierra 1500, 6 with a mileage attached. That is too few to place the failure on the odometer with any confidence.
A part like this is normally expected to survive 120,000 miles. It is the 7th most-reported problem on this model year.
The whole distribution
| 10th | 25th | Median | 75th | 90th |
|---|---|---|---|---|
| — | — | 150,000 miles | — | — |
Read the 10th percentile as “one report in ten arrived this early”. Exact figures are shown in this table because it is the table of record; everywhere else on the site they are rounded to the precision the sample can carry.
What a percentile can and cannot tell you here
These five numbers describe the readings owners gave, in order. The median is the middle one: half the reports arrived below it. The 10th and 90th are the edges of the bulk of the distribution, and the distance between them is the part worth reading. A tight spread — say 70,000 to 95,000 miles — points at something that wears out on a schedule, and the schedule is knowable. A wide one, 20,000 to 190,000, points at a fault that hits some cars and never troubles others, which means the mileage on the listing in front of you tells you very little about your odds.
What these figures are not is a survival curve. Every reading here comes from a car whose owner filed a complaint, so the sample contains only failures: it cannot say what share of the fleet made it past 150,000 miles untouched, because those owners had nothing to report. Nor is the mileage the moment of failure — it is the odometer reading as recalled at the time of filing, which may be weeks later and is sometimes rounded to the nearest ten thousand by the person typing it.
Percentiles are shown at all only once 8 readings exist for the vehicle and mode. Below that the middle of a handful of numbers is noise wearing a decimal point, so the figures are withheld rather than dressed up.
What happens, and what it costs
Putting it right typically runs $500–$6,000 at an independent US shop. That range is an editorial estimate held in this site's failure-mode catalogue, not a figure from NHTSA, and it is a repair cost rather than a diagnosis cost.
The same failure on other years
The same failure is reported on 10 model years of this car. It shows up earliest on the 2006, at a median of 55,000 miles, and latest on the 1999 at 150,000 miles.
By volume the 2003 carries the most reports, with 14; the 1999 has 6. A mode that appears across most years of a model is usually a design choice rather than a bad batch.
If one year stands out to the left, that is the year to avoid; if the whole line sits at a similar mileage, this is wear rather than a defect in one production run.
Tick median reported mileage Solid middle half of reports Faint 10th to 90th percentile Colour how bad the failure is when it happens
What owners wrote
Verbatim from NHTSA complaint narratives, trimmed for length. The mileage is the one the owner gave.
The brake lines under the drivers door on the frame are all rusted and have started to leak from excessive corrosion. Just noticed the leak as the truck was parked outside our house. *tr
While I driving my 1999 gmc sierra 1500 pickup,the brake acted very soft when I was coming to a stop on the roadway. I thought at first that I was low on brake fluid. But was able to drive the truck to my mechanic and he checked it out and found the brake lines had corrosion and a small hole opened up throw brake fluid all under the undercarriage in the rear drivers side of the truck. He told me that this isn't the only truck he has seen this problem. I feel that something needs to addressed soon, before people get hurt or killed because of the loss of there brakes. I was just lucky that I was driving down a hill and the normal speed limit. I think this problem has been occurring and needs to be addressed to gmc to do a recall on all there 1999 gmc trucks. *tr
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…
Also reported on the 1999 GMC Sierra 1500
Loss of braking
ABS module or sensor failure
Brake line, hose or caliper failure
Other brake problem
Other body or interior problem
Parking brake failure
How far this goes
This page is kept out of search results because 6 reports is not enough to publish percentiles from. It stays reachable because somebody looking at this exact car would rather see the reports than be told there are none.
Complaints are voluntary, so 6 is a floor and not a count of affected cars. Mileages are typed in by owners and cluster on round numbers. And the mode itself is assigned by software reading the complaint text, which is reliable in bulk and fallible one report at a time.
Questions this page answers
At what mileage does rust or structural corrosion happen on the 1999 GMC Sierra 1500?
Across 6 owner reports that included an odometer reading, half were filed by 150,000 miles. A quarter were filed before — and a quarter after —. These are the mileages owners reported when they complained, not a prediction for any individual car.
How common is rust or structural corrosion on the 1999 GMC Sierra 1500?
6 reports have been filed with NHTSA, about 0.2 per 1,000 vehicles. Complaints are voluntary, so this is a floor rather than a count of affected cars.
What this is and is not. These are the mileages at which owners chose to complain to a federal agency, which is not the same as the mileage at which the part fails on every car. It skews toward failures that happened outside warranty, cost real money, or frightened someone. It is still the only public dataset that carries failure mileage at all, and the shape of a few hundred readings is informative even when a single one is not. Methodology · JSON · this failure on other cars
Source Owner complaints and recall records published by the US National Highway Traffic Safety Administration, model years 1996–2027 Figures rebuilt Published by AtWhatMileage How every figure is computed