2020 Chevrolet Silverado Electrical System Problems

I went to the store and my brakes were working as normal. When I started my truck to leave I had a hard pedal and there we several warnings on the dash. One said to get service and the other said to limit speed to 43 MPH. I had almost no braking power. Fortunately, I was close to home and the speed limit was 30 MPH all the way home. Once I arrived home I cleared the code with my ODBII scanner and the brakes worked as expected. If I was towing my boat this could have been a bad situation resulting in an accident. I haven't had the same issue in several days however this has to be a huge liability for GM. I'm sure that this is a known failure mode for GM.

Unknown which system failed. While driving on the freeway, truck lost power for a few seconds. Dash lights turned off and back on. Our safety and the safety of others on the freeway were at risk as we had no control of the vehicle. Have not had the truck checked for the problem. Scared to drive it. No warnings appeared.

Odometer Fraud. The contact owns a 2020 Chevrolet Silverado 1500. It was discovered that there was a mileage discrepancy. The contact stated that at the time of purchase, the vehicle mileage was approximately 54,753. The current mileage was approximately 56,000. As per a Carfax report, the contact discovered the vehicle was reported stolen on May 2nd, 2025, with the vehicle mileage at 102,610. The contact was concerned that the odometer was altered prior to the purchase.

I have a Trial Boss and it wont shut off when the key is off, KEEPS RUNNING. Did some research and it gave a couple of thing to check.

The Electronic Parking Brake System on my 2020 Chevy Silverado 1500 continuously malfunctions. Chevy/ GM Customer Support has been made aware of this issue and continues to disregard it entirely. The Electronic Parking Brake, which is an automatic function that cannot be turned off or bypassed, fails to fully disengage when the vehicle is taken out of Park. The Electronic Parking Brake remains very slightly engaged, producing a slight noise while driving and causing excessively premature wear on the vehicles pads and rotors. My vehicle has about 64,000 miles on it, and I have had to replace my rear brakes twice now already, due to this issue. The majority of those 64,000 miles are from uninterrupted highway driving. Each time the rear brakes were replaced, I had the dealership inspect the braking system. The dealership was not able to definitively confirm for some reason but was able to speculate that the aforementioned is likely what is going on. I find that any malfunction of such a critical part of the vehicle and the safety of it's operators and passengers poses a major safety risk.

The wiring harness failed causing erratic and unpredictable behavior at 65 MPH on this 2020 Chevrolet Silverado 1500 with 77,500 miles on the odometer. General Motors no longer makes the wiring harness and there are none available in the market. This otherwise flawless truck (for which I paid $40,000 at a reseller in 2024) is essentially now totaled (undrivable) and GM will not take any responsibility or provide any other remedy beside $750 toward the purchase of a brand new truck.

When a trailer is connected while parked and vehicle is off, trailer lights flicker, blink and sometimes remain on. Sometimes these events will set off alarm also draining battery down.

The rear camera view is skewed resulting in inaccurate reference angles of the vehicle. When used to assist in reversing results in improper placement of vehicle and can cause collision of vehicle with objects.

Odometer Fraud. The contact purchased a 2020 Chevrolet Silverado. The VIN plate was missing from the original location. The contact was able to locate a small VIN plate on the inside of the door. It was discovered that there was a mileage discrepancy. The vehicle was a dealer sale. At the time of purchase, the vehicle mileage was 88,000, and at the time of obtaining a Carfax report, it was discovered that the mileage was 137,164. The contact called the Texas Department of Motor Vehicles.

The contact owns a 2020 Chevrolet Silverado 1500. The contact stated that while at a stop light, the engine shut off as intended in the fuel saver mode, but when the brake pedal was released, the vehicle shut off and failed to restart. The vehicle was towed to the local dealer and was repaired but the repair information was unavailable. The contact stated that failure recently reoccurred and the vehicle was towed back to the dealer. The cause of the failure was not yet determined. The contact stated that the failure had occurred on a busy roadway while the contact’s young daughter was a passenger inside the vehicle. The manufacturer was not yet contacted. The failure mileage was 40,000.

While driving home from work the truck displayed numerous trouble codes including ebc failure, braking failure, traction control failure and trailer brake failure as well as vehicle governed to 42 mph. I took it to the dealership and they checked all of the braking system and could not find any issues. They reset the codes, and changed all 4 pads and rotors as all 4 wheels were 1/32 out of true as a precaution. I drove it home about 5 miles with no issues. The next morning I was on my way to work and the codes reappeared with me being governed to 62 mph. At the stop sign I had no braking at all. Pumping the brakes resulted in no braking or pressure in the pedal. Luckily there was no traffic and I was able to use a hill to stop. I turned around and went the mile back to my house and was unable to stop again ending up with the front end in my neighbors yard. I had the vehicle towed back to the dealership where they still have not found a cause or a solution to the issue

The contact owns a 2020 Chevrolet Silverado. The contact stated that while the vehicle was parked, turned off, and unoccupied, the rear of the vehicle caught fire. The fire was initially extinguished by a maintenance worker, and the fire department later applied water to the area to prevent the fire from reigniting. The fire department was unable to determine the cause of the fire, and a fire report was not provided. The contact was unaware whether a police report was filed. The vehicle was not destroyed or towed. The vehicle was taken to a dealer, where it was diagnosed that the rear wiring harness had failed and needed to be replaced. The dealer also informed the contact that the rear bumper and tailgate were damaged as a result of the failure and would need to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was not available.

The component that failed was the wiring harness installed in the engine area. the harness was installed right next to a dip stick. The dip stick has a sharp metal piece welded to it and it punctured the harness cutting wires on the inside. This could have been a potential fire hazard. The problem was able to be reproduced, inspected and confirmed by a certified chevy mechanic at Philips Chevy in Frankfort, IL. The mechanic also showed me the failure point on the vehicle upon a visit. The dashboard lights were flashing randomly, headlights were very dim which it very difficult to see, android auto stopped working and not able to use hands free, so that became a safety issue, cruise control stopped working, and was receiving errors for a failed fuel pump.

The contact owns a 2020 Chevrolet Silverado 1500. While operating in negative (-41°F) degree winter conditions, the "Service Emission System" entered an EPA-mandated speed limitation in LIMP Mode messages were displayed. Dealer diagnostics confirmed DTC: P20B9 (Heater Control Circuit Open) and P20C1. The failure was identified as the melting of the Diesel Exhaust Fluid (DEF) tank electrical connector due to undersized terminal pins overheating (Joule heating). The contact stated that it was a latent design defect that posed a fire risk and a safety hazard due to sudden loss of motive power in arctic climates (-45°F). General Motors acknowledged the defect in 2500HD models, Special Coverage: N212342980; but excluded the 1500 models. The failure mileage was 29,354.

What happened: In mid-December 2025, my 2020 Silverado 1500 (VIN: [XXX] ) suffered a catastrophic failure of the DEF Tank Assembly (P/N 84914535) at 29,354 miles—less than 30% of its warranted life. This is a latent design defect involving undersized terminal pins that suffer thermal degradation and melt the connector during high-amperage heater operation in arctic conditions (Ref: GM TSB 21-NA-006). Component Availability: The failed assembly is held at the dealership. I have submitted a "Part Preservation Request" to ensure it is available for forensic inspection by federal regulators. Safety Risk: The failure triggers an EPA-mandated "Limp Mode," initiating a software-forced reduction in speed. Unexpectedly losing speed on high-speed, icy Alaskan highways—where roadside snowbanks prevent safe egress—creates an extreme risk of rear-end collisions. Furthermore, a vehicle restricted to 5 MPH or rendered inoperable in temperatures of -30F to -50F poses a direct, life-threatening risk of cold-weather exposure in remote areas. Confirmation: Failure was confirmed by Lithia Chevrolet GMC of Fairbanks on Jan 7, 2026. GDS2 diagnostic verified DTCs P20B9, P20C1, P205D, and P204C. Data was reviewed by the GM District Manager of Aftersales (DMA) and GM Customer Assistance (Case #[XXX]). Warning Symptoms: Check Engine lamp and "Service Emission System" message appeared in mid-Dec 2025, followed by a "Speed Limited" countdown. The electrical disconnect was abrupt due to terminal pin melting, as documented in my forensic engineering report. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

While driving it said "service ESC", "brake system failure" and then "trailer brake system failure" "max speed 62." Brakes when pressed would not work. Had to cruise to stop. When truck shut down and restarted it said "max speed 43" and check engine light came on. Truck was then towed to mechanic and waiting to be looked at/worked on.

There was a brake system failure and the brakes stopped working while going 50 mph

Engine idling rough shaking stalling loss of power

Truck experienced reduce power mode. Took to have codes ran and it showed 24 separate codes when engine light comes on. While riding down the road, truck will go into reduce power mode, shift automatically into 4x4, and several other notifications will appear. Taking to dealership and was told the electrical wiring harness was shorting out causing this issue. Cost around $700 for repair, happened one month later, took it back and no charge for the 2nd time. It is currently in reduced power now. Dealership stated to replace the wiring harness would cost over $3,000. Dealership stated this was a manufactures defect, but no recall was issued so all cost is on the owner.

Odometer Fraud. The contact was attempting to purchase a 2020 Chevrolet Silverado 1500. The contact stated that while attempting to obtain a loan from the bank for the vehicle, it was discovered that there was a mileage discrepancy after obtaining a Carfax report. The vehicle was a private sale. At the time of the initial inquiry on Facebook Marketplace, the vehicle mileage was 63,000. The contact discovered that the mileage was 203,000.