Despite claims that Toyota’s problems with unintended acceleration have been due to driver error, or cured via floor-mat adjustments, a recent case has been reported wherein neither of those factors were relevant. As reported by “Charles” in a message to Engineering Thinking:
The following events occurred on May 15, 2015 while driving from Charleston, SC to Nashville, TN (I-26, I-40) in my 2012 Toyota Highlander. Normally interstate traffic is so congested it prevents use of cruise control; however, that morning I was able to turn it on and set it on 75 MPH. As we were coming up on slower moving traffic, I applied the brakes to switch off the cruise control and it did not work – even after pumping the brake pedal. I then used the off/on on button(switch) on end of cruise control lever to switch off cruise control – and that worked. If that switch had failed – or if I had panicked – then I would have had a “runaway” Toyota. The car did not accelerate, but when you are standing on the brakes and the car is still “cruising” at 75 MPH it sure feels like it is accelerating.
Later on during the same trip I tried the cruise control again (several times actually) and each time applying the brakes would not switch off the cruise control. Whatever is wrong with the cruise control system, on this Toyota, it is what we call in my line of work a “solid fault” – not intermittent. I feel confident that my car will repeat the scenario every time it is tried…
…I am a semi-retired Electrical Engineer with over 40 years in the power industry. For approximately 5 of those 40+ years I worked as a field engineer, testing and commissioning power control systems. So I know a little something about how control systems (cruise or otherwise) are supposed to function. I would like to add, that in my testing/commissioning experience, I only had one programmable relay that failed out-of-the-box, and it was not a software problem. All the problems I encountered were related to wiring and/or wiring design … I strongly suspect the Toyota “problem” may also be related to wiring (wiring harness, assembly process, etc) not software.
…Please note, our Highlander has the factory floor mats which are held in place by two hooks. My cruise control issue had (has) nothing to do with floor mats….
Charles’ expert qualifications and detailed report are compelling evidence that Toyota still has a serious issue that cannot be dismissed by blaming the driver or the floor mats. My thanks to Charles for sharing his experience, and for alerting Toyota owners to the fact that ‘unintended acceleration’ is still a very real possibility.
Prior posts on this issue can be found at the following links:
Stop Driving Recalled Toyotas