Tesla: now we know why some cars accelerate by themselves, and the solution is simple

Tesla: now we know why some cars accelerate by themselves, and the solution is simple

A petition submitted to the relevant US authorities may reopen the case of unintended acceleration peaks reported by several Tesla owners.

Tesla owners are increasingly accusing their cars of accelerating independently and causing accidents. At first, Tesla's management and the U.S. National Highway Traffic Safety Administration blamed all these events on human error: the drivers had pressed their accelerator pedals all the way down. So, case closed? Not really, because the American office responsible for investigating manufacturing defects has received documents showing that the cause could be related to an electrical problem in the Tesla.

On June 29, the Office of Defects Investigations received conclusive explanations for the acceleration spikes reported by Tesla car owners. The document submitted with the petition to reopen the investigation claims that "intermittent demands for high electrical current on the vehicles' 12VDC systems may have caused some or all of the incidents". 

Tesla's unintended acceleration spikes could be caused by an electrical fault

According to the petitioners, "all Tesla vehicles are subject to sudden, involuntary acceleration". It is therefore urgent to reopen the case before this phenomenon claims real victims. In the papers submitted to the authorities, the experts demonstrate that "sudden unintended acceleration may have been caused by a random superposition of a negative-going voltage spike that might have been recorded as if the accelerator was pressed all the way down."

The misinterpretation of this data led Tesla and NHTSA investigators to believe that there had been no hardware or software failure. According to the petitioners, the problem can be solved in a very simple way, since a single software update to the calibration procedure would suffice to make these acceleration spikes disappear.

However, Tesla hacker Jason Hughes believes that the 12-volt drop, described in the petition, is false and can not cause a calibration error that leads to an SUA event. The 12-volt rail is being monitored by multiple modules and Hughes personally analyzed logs from SUA crashes and thinks that the situation described in the petition is impossible.  

"The open source "research" into the Tesla inverters is flawed... which is why the open source controllers always damage the units when used. Tesla's accelerator pedal power, while derived from the 12V system, is using two independent isolated 5V supplies. These run along independently on both sides of the vehicle to the pedal. There is no way for a fault in that system to create the correct signals for full acceleration. It's not possible. If somehow the 12V system were so low it caused the isolated 5V supplies and their capacitors to drop below-expected voltages, that'd sag the entire curve of the dual sensors, leading to a pedal fault, not full acceleration. This is because the supplies for the 5V rail and the redundant ADCs use separate supplies on purpose. It throws the curves out of whack any time either of those isn't getting the required power. Long story short, this is complete nonsense based on faulty analysis of the hardware just like the document that claimed the same based on assumptions a few years back", said Hughes.