My truck continously displays service trailer brake system error on home screen. I have researched the error and found replacing the switch is a simple fix. However in my case this didn't work. I have tried 2 different switches, 1 being GM brand without success. Not sure what else to do. I tow a bumper pull travel trailer and fear this could cause an accident when my family and I are on a…
2020 Chevrolet Silverado HD electrical problems
severe 13 complaints filed with NHTSA · avg repair $850 · see electrical across all vehicles →
Complaints
13
Recalls
0
Avg fix
$850
2fires
What stands out
No new NHTSA electrical complaint has been filed on this vehicle in over 3 years — the issue may be aging out of the active population.
The failure pattern owners describe
Owners of the 2020 Chevrolet Silverado 2500HD are dealing with a cluster of electrical and computer glitches that dealers cannot resolve. The trailering app blacks out or falsely reports disconnected trailer brakes while actively towing—GM acknowledged this as a software issue over three years ago but has not fixed it. Multiple owners report the emergency braking system activating on its own at highway speeds and low speeds alike, nearly causing collisions. The power tailgate opens and closes without warning when wet, a problem that affects 2024 models too.
Random no-start conditions tied to fuel control module failures strand owners without warning. Gear position sensors fail to recognize park, leaving trucks immobilized in remote and dangerous locations. The electric parking brake and hill start assist engage unpredictably while driving or stopped. An even more alarming issue: the diesel exhaust fluid tank connector overheats and burns, creating a fire risk that GM's 2022 service bulletin identified but didn't resolve.
Owners also report a vehicle fire under the hood after routine driving, engine block perforation with piston destruction, water leaking into the stereo amplifier through the rear sliding window, excessive brake pedal effort with diesel exhaust brakes, and trailer brake system errors that persist even after replacing switches. Dealership service visits consistently yield no diagnosis or repair.
Same Chevrolet Silverado HD electrical reports on nearby years: 2019 · 2021 · 2022 · 2023
Failure modes owners describe
Trailering App Malfunction
Built-in trailering application blacks out or displays false trailer-disconnect warnings. Owners report the app becomes non-functional while actively towing, requiring manual brake reconnection and engine restart with no lasting fix.
When: Intermittent; most common during active towing, occasionally works after vehicle sits unused
Symptoms owners cite: Trailering app blacks out completely; False trailer-disconnect error messages; App requires manual restart and brake reconnection
Repairs/costs cited: Dealer unable to repair; multiple service visits to dealerships yield no solution
Recalls/TSBs owners mention: GM Service Bulletin (referenced as 11/5/2020) acknowledges this as a known software issue; GM states they are working on a fix but no solution provided after 3+ years
DEF Tank Electrical Connector Overheating
Diesel exhaust fluid tank electrical connector overheats and burns, creating a fire hazard. Error code P20B9 indicates reductant heater control circuit failure; inspection reveals burned/overheated terminals at the DEF pump module connector.
When: Approximately January 2026 on a 2020 model
Symptoms owners cite: Service emissions error code P20B9; Visible burned/overheated terminals at DEF tank connector; Reductant heater circuit malfunction
Codes mentioned: P20B9
Repairs/costs cited: Dealer diagnosis: Diesel Emissions Fluid Tank Remove and Replace with pump module and harness; burned terminals found during disconnection
Recalls/TSBs owners mention: GM Service Bulletin 21-NA-006 (October 2022) identifies this issue as caused by poor connection at emission reduction fluid tank electrical connector
Fuel Control Module Failure – No-Start Condition
Engine cranks but does not start due to fuel control module malfunction. Problem occurs randomly at unpredictable intervals. Temporary fix involves replacing fuel relay, which resets the system until the next failure. GM identified faulty fuel control modules in multiple new vehicles.
When: Within 3 weeks of purchase (Sept 28, Oct 6, Oct 20, 2020); random recurrence
Symptoms owners cite: Engine cranks but will not start; No fuel delivery; Diagnostic alert generated; Check engine light illuminates until relay is replaced
Repairs/costs cited: Temporary fix: changing fuel relay switch resets system; dealer unable to diagnose root cause; vehicle under warranty at time of complaints
Recalls/TSBs owners mention: Dealer found that fuel control modules were faulty on multiple new GM vehicles; no permanent repair offered
Automatic Emergency Braking System False Activation
Electronic emergency braking system activates without warning during normal driving at both highway and low speeds. Multiple instances nearly caused head-on collisions and rear-end incidents, including one while towing a trailer.
When: Multiple unpredictable occasions since taking possession of new vehicle
Symptoms owners cite: Emergency braking activates spontaneously without warning; False activation at both highway and low speeds; Message: 'service parking brake' displayed on driver information center
Repairs/costs cited: Multiple dealership service attempts with no diagnosis or resolution
Power Tailgate Unlatching – Relay Failure
Power-unlatching tailgate opens and closes on its own without operator input, triggered by a faulty relay that activates when wet. Owner expects this to be recalled; 2024 models reported with the same issue.
When: Unpredictable; triggered by wet conditions
Symptoms owners cite: Tailgate opens and closes repeatedly without warning; Tailgate opens while vehicle is parked and doors are closed; Occurs when tailgate is wet
Recalls/TSBs owners mention: Owner reports expectation of recall for 2020-2024 model years due to faulty relay; references Safety Recall N232426400
Electric Parking Brake Self-Application
Electric parking brake engages automatically while driving, during acceleration from stops, and when exiting the vehicle. Also occurs on level ground without warning.
When: Multiple instances, unpredictable timing
Symptoms owners cite: Electric parking brake applies itself at random times; Self-applies when accelerating from traffic light; Self-applies when exiting vehicle after shifting to park; Occurs on level ground without cause
Repairs/costs cited: Owner has cell phone photos but unable to transfer them for dealer review
Hill Start Assist False Activation
Hill start assist system activates on level ground without warning, applying brake pressure independently of driver input.
When: Unpredictable; reported at traffic lights and level ground
Symptoms owners cite: Hill start assist applies on level ground; Activates at traffic light without cause; Applies brake pressure without warning
Stereo Amplifier Water Damage
Water leaks through the rear sliding window into the stereo amplifier, causing electrical shortage and intermittent volume malfunction.
When: At approximately 63,763 miles
Symptoms owners cite: Radio volume increases and decreases intermittently; No warning light
Repairs/costs cited: Dealer diagnosed water intrusion into amplifier; vehicle not repaired
Recalls/TSBs owners mention: Manufacturer referred contact to NHTSA Hotline
Trailer Brake System Error – Unresolved After Switch Replacement
Continuous service trailer brake system error displays on home screen. Replacing the trailer brake switch, including a genuine GM switch, does not resolve the fault. Owner suspects deeper electrical issue.
When: Unspecified; multiple attempted repairs
Symptoms owners cite: Continuous 'service trailer brake system' error message on home screen
Repairs/costs cited: Two different switches replaced, including OEM GM switch, without success
Gear Position Sensor Failure – Stranding Incidents
Vehicle fails to recognize when transmission is in park, leaving the truck unable to start or creating the false impression that the vehicle is still in gear. Two documented stranding incidents resulted, one in remote mountains causing hours-long battery depletion and a second in a dangerous nighttime location.
When: Multiple unpredictable incidents
Symptoms owners cite: Vehicle does not recognize park gear selection; Unable to start or operate vehicle after shifting to park; Battery becomes depleted while stranded
Excessive Brake Pedal Effort – Diesel Exhaust Brake Issue
When diesel exhaust brake is activated, excessive pedal pressure is required to stop the vehicle on grades, even with no trailer attached. Brakes smell hot after stopping, indicating thermal stress.
When: During operation on expressway ramp with diesel exhaust brake engaged
Symptoms owners cite: Excessive brake pedal pressure needed to stop vehicle on grade; Brakes smell hot after stopping; Issue occurs with diesel exhaust brake on and no trailer attached
Engine Mechanical Failure – Block Perforation and Piston Damage
Engine developed a hole in the block with at least one piston destroyed. Vehicle made strange noises, then oil began spraying from the side of the block after restart attempt.
When: After vehicle sat for a period; occurred on restart
Symptoms owners cite: Strange engine noise before shutdown; Check engine light illumination; Severe spitting of oil from block side; Hole in engine block; Piston destruction
Engine Fire
Vehicle caught fire under the hood after an 80-mile drive to destination. White smoke appeared under hood, followed immediately by large red flames.
When: After 80-mile drive upon arrival at destination
Symptoms owners cite: White smoke from under hood; Large red flames from engine compartment; Fire started with no warning
Synthesized from 13 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 2 most recent
Three days after purchasing my 2020 Chevy 2500 silverado, on september 28th, 2020 around 1253 I tried to start my truck and it wouldn't start. The truck turned over but seemed like it wasn't getting fuel. I then received a diagnostic alert. After changing the relay the truck ran fine. I then scheduled to take it in to the dealer on october 5,2020 to have a diagnostic done on the truck and…
Had electrical trouble with your 2020 Chevrolet Silverado HD?
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 electrical problem on the 2020 Chevrolet Silverado HD?
It's a meaningful issue. 13 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $850.
At what mileage does the electrical typically fail?
Based on the 13 complaints filed, electrical issues most often appear around 24,282 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $850 for electrical 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 electrical?
No active recalls currently cover electrical 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/Chevrolet/Silverado HD.
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.