2021 GMC Yukon electrical system problems

“Water is entering the passenger cabin through failed front sunroof drain tubes on both the left and right sides. The drains discharge inside the A pillars rather than to the exterior, pooling in the driver's side floorboard. An authorized GMC dealer diagnosed the cause in writing on August 12, 2026 as rubber grommet shrinkage and hardened internal buildup preventing water from flowing through, on both the left and right sides simultaneously. The identical bilateral failure mode indicates a component or assembly defect rather than debris blockage. Water is accumulating in the driver's footwell in proximity to cabin electrical components and the fuse block area, creating a risk of electrical shorting, connector corrosion, and circuit failure. Mold has developed in the front carpet and padding on the driver's side, and water intrusion staining is present on the passenger side. The dealer has quoted 2,727.16 to replace the drain tubes and the mold-damaged carpet and padding. The vehicle entered service on February 5, 2025 and has 45,211 miles. GM has issued service bulletin 20-NA-219 addressing sunroof drain hoses on 2021 Yukon, Yukon XL, Tahoe, Suburban, and Escalade models.”

“While driving the vehicle on the interstate, the vehicle shifted to neutral without warning. Our daughter was able to fortunately coast to the side of the interstate without incident. The vehicle was shut off and attempted to turn back on without success, so vehicle was towed to Lugoff Chevy dealership where repairs are always performed. The dealership stated the problem was related to fuse block melted and shorted. The problem was fixed; however, I am not convinced that this shouldn't be something requiring a recall and needs further investigation. There was no warning lamps, messages, or symptoms prior to the failure.”

“1. What component or system failed or malfunctioned. The Fuel Pump Module failed unexpectedly while the vehicle was being driven. Failure caused the engine to stall, resulting in a complete loss of power and mobility. Unsure if part is available for inspection. 2021 GMC Yukon have a recall N252516900, but our VIN is not included in this. Can our VIN be added to this recall please? 2. How was your safety or the safety of others put at risk? The vehicle abruptly stalled while being driven through a parking lot, causing a complete loss of power and leaving the vehicle disabled in an active traffic area. Because the vehicle could not be shifted out of PARK, it became an obstruction, creating a hazard for other drivers navigating the parking lot and increasing the risk of a collision. 3. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. After the vehicle was towed to a local mechanic on a flatbed truck, the dealer diagnosed and confirmed that the Fuel Pump Module had failed, which caused the vehicle to stall and lose power. 4. Has the vehicle or component been inspected by the manufacturer, police, insurance…”

“As I was driving, the vehicle's air conditioning suddenly began blowing warm/hot air. Moments later, the check engine light and all electronic service stability lights illuminated on the dashboard. Simultaneously, the vehicle suffered a complete loss of electronic brake assist, resulting in an extremely hard brake pedal and a severe reduction in braking power. The vehicle also displayed a "No Drive Mode Available" message. Third-party diagnostic scanning revealed network power codes U3018, U3505, P00FF, and P0700, indicating a total loss of power to the Body Control Module (BCM). This is the second life-threatening incident with this vehicle I have experienced following a previous highway engine stall due to engine recall. The vehicle was towed to a GM dealership for diagnostic and emergency electrical repairs.”

“The driver's seat inboard airbag assembly and internal structural wiring harness failed due to a direct short circuit, completely deactivating the vehicle's supplemental restraint system. General Motors has a known engineering bulletin for this issue (#23-NA-085), noting that sharp internal seat frame components slice the airbag wiring harness. Rather than permanently fixing this structural design flaw while under warranty, dealership technicians repeatedly executed temporary, non-compliant field patches, including plastic zip-ties and Velcro tape inside the cushion. These temporary patches continuously failed, leaving the airbags disabled. Furthermore, the vehicle was sold under "Certified Pre-Owned" designation with an active, uncompleted 2020 manufacturer Customer Satisfaction Program Campaign (#N202310850-02) for this exact airbag circuit defect. Component failed & available for inspection: The driver's seat inboard airbag assembly and internal structural wiring harness failed due to a direct short circuit. The components are available for inspection inside the vehicle at the servicing dealership. Safety risk: Safety was put at extreme risk because active…”

“The contact owns a 2021 GMC Yukon. The contact stated that while driving approximately driving 45 MPH and turning onto an exit the vehicle suddenly reduce speed and lost power and the message "Press Start" had displayed. The contact stopped the vehicle and eventually restarted the engine and the vehicle operated as normal. The next day the vehicle was driven to the local dealer who was unable to duplicate the problem and determine the cause of the failure. The manufacturer was not yet contact regarding the failure. The failure mileage was 42,000.”