2020 Chevrolet Silverado Electrical System Problems

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.

There is an issue with the wiring harness that causes vehicle to lose power. Dealership says manufacturer defect because designed with harness cover is too thin and is to close to engine so burns wires. Many other users have complained of this issue and is frequent in this model.

Vehicle started and behaved as expected when leaving my home and for a dozen lights or so between my home and place of the incident. While stopped at a red light, the auto stop function shut the truck down as normal. On re-start when getting green light, after releasing brake pressure, the start up was belabored for two turnovers before starting up. As I pulled off the stop with a green light, the dash lights illuminated and display started rolling through system failures, one of which was the brakes system and ESC. I cautiously proceeded through my turn to a thankfully quiet intersection as the brakes were completely unresponsive. I had ZERO brake function. I was able to slowly come to a rolling stop enough to get the truck in park where I turned it off and back on and the brake function returned. I cautiously drove to the local chevy dealer where I was informed that the battery drain pulls from low voltage when it needs extra power for start up. This is utterly terrifying that it is even possible for the battery to start the truck WITHOUT ANY BRAKE FUNCTION. Had this happened just two lights before or after where I was, it would have been a news headline. I could have easily been headed up and over a bridge leading to a catastrophic event at the bottom where I would have been completely unable to stop my truck by any means other than a collision. I would have preferred a dead battery at a red light. Seems a whole lot safer. I'm now stressed beyond measure at the thought of some failure in the future that could lead to another event such as this. My truck is now a nightmare wondering what electrical malfunction is going to put me and/or my wife and daughter in a life or death situation, let alone others on the road. This shouldn't even be an option for the truck to start at the expense of a critical safety function. Not to mention there is no function for the auto start stop system to be deactivated permanently by my choice. I am beside myself and scared to drive.

The contact owned a 2020 Chevrolet Silverado 1500. The contact stated that while stopped at a stop light, he observed smoke emanating from the area of the vehicle between the cab and the bed, prompting him and the other occupants to quickly evacuate. Within moments, the vehicle caught fire and was engulfed in flames. Local emergency services arrived and were able to extinguish the fire. The contact was informed that fire investigators on scene determined that the fire had appeared to originate in the electrical system associated with the seat belt located behind the rear passenger side seat. No warning lights were illuminated. The vehicle was towed to a tow yard and was likely to be deemed a total loss by the contact's insurance provider. A fire report was filed. A police report was filed, and no injuries were reported. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 19V814000 (Seat Belts); the VIN was included, but the vehicle had already been repaired. The manufacturer was not notified of the failure. The failure mileage was 100,000.

Shop has had the truck over two months and cannot figure out the problem will not go stuck in limp mode.

I’m reporting a safety concern involving a 2020 Chevrolet Silverado 1500 with the 3.0L Duramax diesel engine. The vehicle went into limp mode and died on the side of the road. AAA installed a new battery, which temporarily restored operation, though the “Service Charging System” warning remained. I drove it home, let it sit for several days, and then took it to a Chevrolet dealership. Although the warning light had cleared, I brought it in out of caution. The first dealer diagnosed a failed alternator and recommended replacement at a cost of $2,158.75. I was also told the vehicle was not included in any active recalls related to this issue. Believing the price was high and wanting a second opinion, I went to another Chevrolet dealer. They ran the same diagnostic and found no issue with the alternator or generator, charging only a diagnostic fee. They also said if the alternator had needed replacement, the cost would have been around $1,300. I mentioned to both dealers that I had seen similar alternator/charging system failures recalled on other 2020 Silverado models. Online forums and customer complaints suggest that many Silverado 1500 trucks with the 3.0L Duramax are experiencing similar problems, indicating a potentially broader issue. Given the inconsistency in diagnostics, the significant cost discrepancy, and the number of similar consumer reports, I believe this issue may be more widespread than current recalls reflect. I respectfully request that NHTSA investigate whether the existing recall should be expanded or if a new recall should be issued for 2020 Silverado 1500 models equipped with the 3.0L Duramax. This issue occurred shortly after a separate failure related to the NOx sensor, which I am submitting under a separate complaint.

My 2020 Silverado duramax was at the dealer for recall , next day check engine light came on and rear wheels got locked up , the dealer installed new transmission valve , next day same problem check engine light and rear wheels locked up again, now the dealer said is something to be with a speed sensor and I have to paid for it , my truck was perfectly working before all this recall thing, it’s been 3 weeks now with no transportation, because GM and Chevy dealer don’t want to respond or fix this problem with the transmission valve and transmission control module software that was installed My truck was all good before this matter

The contact owns a 2020 Chevrolet Silverado 1500. The contact stated while driving at approximately 15-20 MPH, the message “Engine Power Reduced” was displayed on the instrument panel, and the vehicle started shaking and decelerating. The vehicle was taken to the dealer who diagnosed that the engine wiring harness needed to be replaced. The dealer informed the contact that another part needed to be replaced; however, the contact was unable to recall the exact part. The vehicle was not repaired. The manufacturer was informed of the failure and informed the contact of a possible number for assistance. The manufacturer had opened a case regarding the failure. The failure mileage was approximately 124,000.

My break system failed twice in 2 weeks. On Feb 01, 2025 around 5:35 pm, I almost ran over a dog the first time because I lost access to breaks and emergency breaks and could not stop going through my neighborhood. Today on Feb 13, 2025, I had picked my son up from school, and the breaks went out after we left the school. This time I almost ran into a car but had to turn off to the right to avoid hitting it. My son and I could have injured the person driving in front of us and ourselves. I looked up the problem, and it seems that many others have faced the same problem. When I turned off the truck for 10 minutes, the system would reset itself and start working normally again. I took the truck to the shop, and it is currently there so they can run tests on it. I recorded what it looks like on the dash when I lose all braking.

Vehicle has been in and out of service for the past 5 months with multiple alerts including "Brake system failure 43mph top speed," "service esc," "service brake assist." On major interstate car would not accelerate past 43mph putting myself, infant, toddler, and wife in danger. Multiple attempts have been made to repair the vehicle and nothing has been successful. Lifters, CAM, torque converter, EBCM, master cylinder, calipers, and the list goes on. When this happens the brake is extremely hard to press making it difficult to stop the vehicle. Issue has been reproduced by dealer and attempts have been made under warranty to repair. Car only has 36k miles on it and the issue began prior to that. GM ongoing solution is to bleed the brakes, which clearly has not resolved the issue. Still hear ticking and noises from engine. Something needs to be done to remedy this issue. This is a safety hazard for myself, my family, and everyone driving around me.