2024 Toyota Grand Highlander power train problems

“Transmission Whining Noise Detected, Automatic Shifting Difficulties, Reduced Power & Acceleration Concerns. Dealer inspected and confirmed transmission failure. Required Dealer replacement under power train warranty. Defect known to exist in Toyota 6 speed Automatic U80A transmissions. Transmission is known to be defective and unreliable, potentially causing catostrophic injury to persons and property with use and operation.”

“Incident occurred on XXX at 9:46AM PST, [XXX]. When applying brakes normally to come to a gradual stop behind another vehicle stopped at a stop sign on a slight decline, PCS collision warning lights enabled and vehicle lurched forward while my foot was on brake. This is not to be confused with automatic braking behavior as front collision warning lights in driver information center flashed red. Rather, vehicle lurched forward as if accelerating once within feet of vehicle in front. Then, vehicle rocked front to back multiple times with my foot still on the brake, as if Drive and Reverse was being quickly and intermittently engaged back and forth about 1 second apart. Had my foot not been firmly on the brake, the vehicle felt like it would travel forward and then back (colliding with vehicle in front and in back) without driver inputs. While car continued to lurch forward and then back, I shifted transmission into Park then back in Drive, and behavior stopped. There was a loud clunk as the car engaged in Drive. This has occurred 3 times over the past 2.5 years. What is even more curious, is that this occurred all 3 times at the same stop sign, which is at a…”

“2024 Toyota Grand Highlander Hybrid AWD. Vehicle exhibits a severe metallic "clunk" or "boom" noise and impact from the undercarriage specifically when reversing under moderate to firm acceleration. This is a recurring issue reported by numerous owners of this model, related to harsh powertrain engagement and movement when changing direction under load. This issue is NOT related to wheel rotation, brakes, or CV axles. The vehicle has approximately 70,000 miles, has been driven strictly on paved roads with no towing or off-road use, and has no active warning lights. The sudden mechanical shock while engaging reverse poses a potential safety and reliability concern regarding drivetrain components.”

“2024 Toyota Grand Highlander XLE FWD. At approximately 38,000 miles I began hearing a roaring/humming noise that varied with vehicle speed. The condition initially progressed slowly but then became much worse within several days. At 41,510 miles a Toyota dealer diagnosed and replaced the right rear hub/wheel bearing assembly. I was advised that the failed bearing was nearly seized when removed. After replacement the noise was reduced but remained present. The dealer was uncertain whether another bearing was failing and initially believed the remaining noise could be tire noise, advising me to monitor it. The noise again deteriorated rapidly and became severe enough that I considered the vehicle unsafe to drive. At 42,223 miles the same dealer diagnosed and replaced the left rear hub/wheel bearing assembly. The noise disappeared after replacement. Both rear wheel bearings therefore failed at approximately 40,000–42,000 miles within about 700 miles of each other. The vehicle has no known accident or suspension damage and the dealer identified no other condition causing the failures. I am concerned that rapid deterioration or seizure of a wheel bearing while…”

“When ambient temperature are over ~90 the vehicle will lose power during acceleration. This happens typically in the speed range of ~20-35mph. The vehicle’s rpm will spike high but lose the ability to increase speed or shift gears. This occurs ~ 40-50% of the time when over 90 degrees. On several occasions we were forced to abandon merging onto the highway because the vehicle wasn’t safely able to accelerate to match the speed of vehicles on the highway. We reported this issue to our local Toyota dealer September 2025. After reviewing the vehicle they said nothing was wrong. We had them drive it longer and they agreed the vehicle had these issues. The dealership spoke with Toyota and they confirmed there was an issue for our vehicle and a lot of others and they had no fix for it. That was September 30, 2025; Toyota Brand Engagement Center Reference # 250923001413. There has been no communication from Toyota or our dealer since then. The safety issue with the vehicle is a major concern in operation of the vehicle and with the hot climate we live in, is putting our occupants and others on the road at risk and we feel Toyota needs to be held accountable for…”

“At 5:16 pm, CST. I was stopped at a stop sign headed west on a 25 mph road crossing a 30 mph road (that does not have a stop sign) in Illinois. After waiting for a an appropriate gap in traffic, I attempted to accelerate though the interesting. I released the brake pedal and attempted to accelerate. The vehicle barely accelerated. The engine seemed to minimally climb in RPM and only accelerated minimally out into the cross road. This lasted approximately 1-2 seconds. AT this point I was fully into the first lane of traffic. I then fully depressed the accelerator to try to get the vehicle to respond and after approximately a 0.5 to 1.0 second delay the engine fully responded and I was able to accelerate out of the oncoming cross traffic. This is by no-means the first time this behavior has happened with this vehicle but it is the first time I'm reporting it to the NHTSA.”