My pickup was specifically purchased to pull a duel axle trailer ( brakes required by Fl. Law). The trailer weights more than the pick up. They stopped working with the electric /hydrolic Trailer brake system. I have had the Sierra in three times for Warren Ty repair. They never fixed the system. I have thoroughly test the trailer system - it works fine with another pickup. Dealer won’t…
2020 GMC Sierra brakes problems
severe 24 complaints filed with NHTSA · avg repair $450 · see brakes across all vehicles →
Failure mileage
Complaints
24
Recalls
0
Avg fix
$450
2crashes
1fire
2injuries
The failure pattern owners describe
The 2020 GMC Sierra brake complaints center on sudden loss of braking function—the most critical safety failure. Owners describe the brake pedal going soft or unresponsive with no warning, forcing them to downshift or coast to avoid collisions. This happens at all speeds and occurs early (under 200 miles on one brand-new truck) through higher mileages. A "Do not exceed 62 MPH" warning often appears alongside ABS, brake system failure, and ESC alerts. Restarting the engine temporarily clears the issue, but it recurs.
A second group of complaints involves unintended braking—brakes locking suddenly without driver input, immobilizing the vehicle for hours until mysteriously releasing. Brake pad sensors are also misfiring, warning of service urgently needed despite pads showing 80–90% wear remaining.
Trailer brake systems fail intermittently during towing; electrical faults cascade through ABS, traction control, and power steering simultaneously. Dealership repairs include master cylinder and ABS module replacement (with some modules reportedly dead on arrival). One owner states GMC told them they're fielding many calls about AT4 models but won't issue a recall. Another's dealership blamed a bad battery for triggering the entire brake failure cascade. Costs exceed $3,000, and multiple owners report the problem persists after repair or the dealer cannot replicate it.
Same GMC Sierra brakes reports on nearby years: 2017 · 2018 · 2019 · 2021 · 2022
Failure modes owners describe
Complete or severe brake pressure loss while driving
Brake pedal loses responsiveness or goes completely soft; vehicle loses braking ability and must be stopped by downshifting or coasting. Often accompanied by ABS, brake system failure, and ESC warnings. Typically clears after engine restart.
When: Variable; reported as early as 120 miles, 7,020 miles, 15,700 miles, and at higher mileages through 102,000 miles. Some owners report multiple occurrences.
Symptoms owners cite: No brake pressure or extremely soft brake pedal; Vehicle continues to roll or accelerate despite braking; Brake pedal feels loose or unresponsive; Brakes require full force application with minimal stopping power; ABS warning light illuminated; Brake system failure warning displayed; ESC/traction control warnings; Check engine light; Speed-limit warnings ('Do not exceed 62 MPH' or other limits); Message: 'Brake Failure System' or 'Brake System Failure'; Trailer brake failure warnings
Codes mentioned: ABS fault codes, Brake system failure codes, Low voltage codes (caliper sensor), Trailer brake system codes
Repairs/costs cited: Dealer replacements cited: master brake booster, ABS module (both reportedly failed/bricked on first install requiring second replacement), master cylinder ($3,000+ cost mentioned), rear caliper replacement, computer system upgrades. One owner reports dealership unable to diagnose intermittent issue after multiple visits.
Recalls/TSBs owners mention: GMC acknowledged receiving many calls about this issue on AT4 vehicles but refused to issue recall. Some owners told issue is a 'known issue' but VIN not under recall. Partial warranty coverage offered in one case. Service bulletins or recalls referenced: NHTSA Campaign 20V116000 (Service Brakes, Hydraulic), recall N192264451, EA25007 (Engine/Engine Cooling).
Unintended brake application and lockup
Brakes suddenly activate without driver input, causing rapid deceleration or full lockup. Vehicle becomes immobile and brakes do not release. Condition clears after hours or overnight.
When: Intermittent; reported in driveway and on streets. One owner reports five occurrences.
Symptoms owners cite: Sudden unintended braking without driver action; Brakes lock and do not release; Vehicle immobilized and cannot be moved; Shifting gears does not release brakes; Engine off/restart does not release brakes; 'Brake Failure System' message on information screen; Issue resolves after hours or overnight
Repairs/costs cited: Dealership unable to locate cause after two tow-truck visits and diagnostic tests. Issue remains unresolved.
Brake pad wear sensor malfunction
Brake pad monitoring system alerts and warns of low brake life when pads are actually serviceable. System shows conflicting wear percentages or falsely indicates urgent need for service within days.
When: Early in vehicle operation; one owner reports alert came after front brakes showed high 80% and rear in low 90% remaining, alert appearing within one week and less than 200 miles.
Symptoms owners cite: Brake pad monitoring alert on driver information center; Warning light or message indicating brake service needed; Conflicting brake wear percentages (e.g., high 80s/low 90s then suddenly alert); Message 'Brake Monitor' or similar warning; Message '1 More Mile Left to Drive' after brake service; No observable brake issues (no pulsing, noise, or chattering)
Repairs/costs cited: Dealer advised brake pad replacement; computer did not recognize repair on one vehicle. One owner cites NHTSA recall N192264451 (for 2019 Sierra/Cadillac but not documented for 2020) as potentially related.
Recalls/TSBs owners mention: Dealers and GM customer service directed owners to perform service at owner expense. Safety bulletin exists for 2019 model year but not (per owner report) for 2020.
Trailer brake system intermittent failure
Trailer brake function randomly disengages or stops working while towing. Other vehicle systems (turn signals, lights) may also malfunction coincidentally.
When: Occurs during towing at various speeds; reported as early as under 10k miles and recurring multiple times per year.
Symptoms owners cite: Trailer brakes stop working while driving; Brake function intermittently returns or remains offline; Trailer brake warning light; Other electrical systems fail (turn signals, lights); Issue does not occur consistently when at dealership for diagnosis
Codes mentioned: Trailer brake system codes
Repairs/costs cited: Dealership unable to diagnose; states issue must occur at dealership to replicate. Owner has video evidence but issue remains unresolved after multiple visits and warranty attempts.
Hard brake pedal / brake assist failure
Brake pedal feels excessively firm or unresponsive; brake booster assistance not functioning. Requires excessive force to achieve normal stopping.
When: Early to mid-vehicle life; reported at 16,200 miles.
Symptoms owners cite: Hard brake pedal; Brake assist failure; Excessive pedal pressure required to stop; Brake failure warning codes
Codes mentioned: Master cylinder fault codes, Brake system failure codes
Repairs/costs cited: Master cylinder replacement recommended (approx. $3,000); no physical fluid loss observed.
Recalls/TSBs owners mention: Manufacturer denied liability despite no observable leak and known similar issues on 2020 models.
Brake system electrical/sensor faults
Cascading fault codes involving brake system, ABS, ESC, and related electrical components; often triggered by or concurrent with other electrical issues (battery, alternator, wiring harness).
When: Variable; some early (7,000+ miles), others at higher mileage (44,000 miles).
Symptoms owners cite: Multiple warning lights simultaneously (brake, ABS, check engine, ESC, traction control, power steering failure); Brake system failure warnings; Speed limiting messages; OnStar ABS alerts; Trailer brake warning lights; Steering assist reduced messages
Codes mentioned: ABS codes, Low voltage caliper sensor codes, Brake system codes, Electrical module faults
Repairs/costs cited: Repairs cited: AGM battery replacement, alternator cooler, wiring harness repairs, electrical module diagnostics. One vehicle repaired but failures recurred.
Recalls/TSBs owners mention: OnStar sent alerts instructing visit within 7 days for ABS issues. Manufacturer has not provided diagnosis or assistance in some cases.
Brake squeal at low mileage
Continuous squealing noise from brake system starting at very low mileage.
When: As early as 4,000 miles.
Symptoms owners cite: Brake squeal noise
Repairs/costs cited: Dealer claims condition is normal; no repair offered.
Recalls/TSBs owners mention: Dealer states issue is normal operation.
Synthesized from 24 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 1 most recent
Had brakes trouble with your 2020 GMC Sierra?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the brakes problem on the 2020 GMC Sierra?
It's a meaningful issue. 24 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $450.
At what mileage does the brakes typically fail?
Across the 9 complaints that reported odometer mileage, most brakes failures cluster between 7,020 and 69,000 miles, with the median around 44,000. A quarter of owners report trouble before 7,020; a quarter make it past 69,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $450 for brakes repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to brakes?
No active recalls currently cover brakes issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2020/GMC/Sierra.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.