This page covers 5 recalls and 19 owner complaints for the 2021 GMC Sierra 3500.
Powertrain complaints dominate what owners of the 2021 GMC Sierra 3500 report, with the transmission drawing the most attention. Owners describe moments where the transmission behaves as if it's in neutral during acceleration, with the truck failing to engage and move as expected. The electrical system accounts for the next cluster of reports, covering a range of symptoms: a false "Shift to Park" warning that prevents the truck from shutting off while the vehicle is already in park, a backup camera displaying a misaligned image that appears to show the ground roughly ten feet behind the truck, and a rear defroster that caused plastic near the rear sliding window to melt and smoke during normal use. Key fob sensitivity also surfaces, with at least one owner describing unintended locking and unlocking when the fob is carried in a pocket.
19
Total Complaints
By System
The 2021 GMC Sierra 3500 has 5 recalls, the most serious being a brake system fire risk and a transmission defect on diesel-equipped trucks where the rear wheels can lock up without warning, raising the risk of a crash.
Two recalls affect seatbelts: in one, the bracket securing the front-row center seat belt may not be attached to the seat frame, and in the other, incorrect bolts may have been used to fasten seat belt assemblies elsewhere in the vehicle. In both cases, the belt may not hold an occupant in a crash. On the brake side, loose bolts on the brake pressure modulator valve assembly can allow water inside, where it can cause an electrical short and a fire. There is also a tailgate concern on trucks with power-unlatching tailgates: water can short the electronic release switch and cause the tailgate to open on its own while driving, dropping cargo onto the road.
At a glance
What can fail
The transmission control valve may fail, causing the rear wheels to lock up unexpectedly.
What the fix does
Dealers will install updated transmission control module software and repair or replace defective control valves as needed.
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Complaints are owner-reported and reflect individual experiences, not confirmed defects. They are distinct from recalls. Data sourced from the national vehicle safety complaint database. See trending complaints →
Summarized — see the official notice for exact wording, dates, and contacts.
At a glance
What can fail
Water can get inside the tailgate's electronic release switch and cause it to short circuit, making the tailgate unlatch on its own while parked.
What the fix does
Dealers will replace the exterior touchpad switch assembly at no cost to fix the electrical short and prevent unintended unlatching.
Summarized — see the official notice for exact wording, dates, and contacts.
At a glance
What can fail
Bolts securing the brake pressure modulator valve assembly may not be tight enough, allowing water to enter and potentially causing brake system failure.
What the fix does
Dealers will replace the brake pressure modulator valve assembly at no cost to you.
Summarized — see the official notice for exact wording, dates, and contacts.
At a glance
What can fail
Seat belt fastening bolts may be incorrect, causing seat belts to not attach properly to the vehicle.
What the fix does
Dealers will replace the suspect bolts with correct ones at no cost to you.
Summarized — see the official notice for exact wording, dates, and contacts.
At a glance
What can fail
The seat belt brackets in the front-row center seating position may not be properly secured to the seat frame, reducing their ability to restrain occupants.
What the fix does
Dealers will inspect the seat belt bracket attachments on both sides and reassemble them correctly if needed, at no cost.
Summarized — see the official notice for exact wording, dates, and contacts.
