My 2009 Toyota Highlander Hybrid makes an intermittent noise when I accelerate from a stop or decelerate to a stop. My best description of the sound is a sharp thud or a dull knock (maybe a dull pop). It happens almost exclusively when I accelerate from a full stop or from moving very slowly. A similar sound happens when I decelerate to a full or near stop. I’m very certain that the sound is coming from the rear suspension or drive train of the vehicle, but I have not proven it. When I’m moving along at normal speeds, I don’t hear any sounds and the car feels solid. By pure luck, going over the right sort of bumps causes a somewhat similar noise, but that might be a read herring.
Trips to two separate Toyota dealers have not fixed the issue since it is not easily repeatable. The first dealer tried tightening some bolts. The second replaced one of the front(!) struts, tightened bolts and lubricated things. I have managed to reproduce the issue for the second dealer, but the noise wasn’t persistent enough for them to track it down.
This type of SUV should be regarded as all-wheel-drive, but power is mostly delivered by the front tires. The rear tires are driven by an independent electric motor and differential. The front and rear drive trains operate separately; the only mechanical connection between them is the rest of the vehicle.
I’m wondering if the electric motor could be slipping a little bit.
Respectfully submitted to the Car Talk Community by Erik.