Incident: Toyota Prius Cruise Control Acceleration Software Failure Incident

Published Date: 2010-02-11

Postmortem Analysis
Timeline 1. The software failure incident involving the Toyota Prius cruise control issue happened in October 2008 as reported in Article 595.
System 1. Cruise control system in Toyota Prius vehicles, including the 2010 model [595].
Responsible Organization 1. Bad software was blamed for the acceleration issue in Toyota Prius by Steve Wozniak, the co-founder of Apple, and some Prius owners [595]. 2. The dealership that fixed the car initially blamed the problem on floor mats, indicating a possible misdiagnosis of the software issue by the service center [595].
Impacted Organization 1. Toyota owners, including Steve Wozniak and other Prius owners, experienced the software failure incident where the Prius accelerated unexpectedly while in cruise control mode, causing safety concerns and potential dangerous situations [595].
Software Causes 1. Bad software causing the accelerator to go wild under certain conditions of cruise control, as reported by Steve Wozniak and other Prius owners [595].
Non-software Causes 1. Floor mats and sticky accelerator pedal were identified as potential causes by Toyota, rather than software issues [595].
Impacts 1. Drivers experienced sudden acceleration while in cruise control, causing their vehicles to speed up uncontrollably and resist braking efforts, leading to dangerous situations on the road [595]. 2. Owners reported instances where the cruise control feature did not respond as intended, causing the car to accelerate unexpectedly and creating a potential safety hazard [595]. 3. The incidents led to concerns among owners about the safety of driving their vehicles, with some expressing fear and uncertainty about the reliability of the cruise control system [595]. 4. The software failure incident resulted in owners losing trust in the manufacturer's response, as some felt that Toyota was dismissive of their complaints and attributed the issue to floor mats or driver error rather than addressing the underlying software problem [595].
Preventions 1. Implementing thorough software testing procedures to identify and address potential issues before the product release [595]. 2. Conducting comprehensive software quality assurance checks to ensure the cruise control system functions correctly under all conditions [595]. 3. Establishing a more efficient and responsive communication channel for customers and experts to report software-related concerns to the manufacturer [595]. 4. Enhancing collaboration between the manufacturer, regulatory agencies, and independent safety organizations to investigate and address reported software failures promptly [595].
Fixes 1. Conduct a thorough investigation into the software controlling the cruise control system in the Toyota Prius to identify and rectify any bugs or faults [595]. 2. Implement software updates or patches to address the issue of erratic acceleration during cruise control operation [595]. 3. Collaborate with experts in software engineering and automotive technology to ensure the cruise control software functions reliably and safely [595]. 4. Enhance communication channels for consumers like Steve Wozniak to report software-related issues directly to Toyota and relevant regulatory agencies for prompt action [595]. 5. Provide clear and detailed information in the owner's manual about the functionality and limitations of features like "adaptive cruise" to prevent misunderstandings that could lead to software-related incidents [595].
References 1. Steve Wozniak, the co-founder of Apple and owner of several Priuses, including a 2010 model [595]. 2. Clarence Ditlow, the executive director of the Center for Auto Safety [595]. 3. Various owners of Toyota Prius models who experienced the cruise control issue [595]. 4. Federal lawmakers, including the chairman of the House Committee on Oversight and Government Reform, Rep. Edolphus Towns [595]. 5. Grover Walton and Herb Kuehn, who experienced the cruise control issue firsthand [595]. 6. Donald Friedman, an electrical engineer with experience in the auto industry and NHTSA [595].

Software Taxonomy of Faults

Category Option Rationale
Recurring one_organization, multiple_organization (a) The software failure incident having happened again at one_organization: - The article reports incidents where Toyota Prius owners experienced acceleration issues related to cruise control, which some attributed to bad software [595]. - Owners reported that when they resumed cruise control, the car took off unexpectedly and resisted when they tried to brake, indicating a software-related problem [595]. - The article mentions that Toyota Prius owners experienced similar cruise control issues in previous models as well, suggesting a recurring software-related problem within the same organization [595]. (b) The software failure incident having happened again at multiple_organization: - The article mentions that cruise control problems have been reported in other vehicles as well, such as Ford vehicles, which had a recall due to faulty cruise control switches [595]. - The article highlights that many automakers have faced cruise control issues over the years, indicating that this type of software-related problem is not unique to Toyota [595].
Phase (Design/Operation) design, operation (a) The software failure incident related to the design phase can be seen in the article where Steve Wozniak, the co-founder of Apple, pointed out that the issue with the Toyota Prius accelerator going wild was not due to floor mats or a sticky accelerator pedal, as Toyota claimed, but rather blamed it on bad software [595]. This indicates that the problem was introduced during the system development phase. (b) The software failure incident related to the operation phase is evident in the experiences shared by Toyota Prius owners who reported that when they resumed cruise control, the car took off unexpectedly and resisted when they tried to brake, indicating a failure introduced during the operation or misuse of the system [595].
Boundary (Internal/External) within_system (a) within_system: The software failure incident related to the Toyota Prius acceleration issue was attributed to bad software by Steve Wozniak, the co-founder of Apple, and owner of several Priuses [595]. The problem was specifically linked to the accelerator going wild under a certain condition of cruise control, indicating an issue originating from within the system's software. Additionally, Clarence Ditlow from the Center for Auto Safety mentioned receiving complaints from Prius owners about the vehicle behaving erratically, further suggesting an internal software issue [595]. (b) outside_system: The articles do not provide information indicating that the software failure incident related to the Toyota Prius acceleration issue was due to contributing factors originating from outside the system.
Nature (Human/Non-human) non-human_actions (a) The software failure incident occurring due to non-human actions: The software failure in the Toyota Prius cruise control system was attributed to bad software by Steve Wozniak, the co-founder of Apple, and owner of several Priuses, including a 2010 model [595]. Wozniak mentioned that the accelerator went wild under a certain condition of cruise control, indicating a failure introduced by the software itself rather than external human actions. (b) The software failure incident occurring due to human actions: There is no specific mention in the articles about the software failure incident in the Toyota Prius cruise control system being directly caused by human actions. The focus of the reports is primarily on the software issue itself and the challenges faced by owners in addressing the problem with Toyota and regulatory agencies.
Dimension (Hardware/Software) hardware, software (a) The software failure incident occurring due to hardware: - The article mentions that Toyota had maintained that the acceleration issue was not due to floor mats or a sticky accelerator pedal but was blamed on bad software by Steve Wozniak, the co-founder of Apple [595]. - Owners of previous Prius models reported experiencing the same problem where the car took off unexpectedly when they resumed cruise control, indicating a hardware-related issue [595]. (b) The software failure incident occurring due to software: - Steve Wozniak blamed the acceleration issue on bad software in the 2010 Prius model, indicating a software-related problem [595]. - The article discusses the complexity of modern automobiles with multiple computer processors controlling various functions, suggesting that the issue could be related to software communication and coordination problems [595].
Objective (Malicious/Non-malicious) non-malicious (a) The articles do not provide any information indicating that the software failure incident related to the Toyota Prius acceleration issue was malicious in nature. There is no mention of intentional actions by individuals to harm the system through the software failure incident [595]. (b) The software failure incident related to the Toyota Prius acceleration issue was non-malicious in nature. The issue was attributed to bad software by Steve Wozniak, the co-founder of Apple, and was not linked to intentional harm but rather to a flaw in the software that caused the acceleration problem [595].
Intent (Poor/Accidental Decisions) poor_decisions, accidental_decisions (a) In the reported software failure incident related to the Toyota Prius acceleration issue, the failure can be attributed to poor_decisions. Steve Wozniak, the co-founder of Apple, blamed the problem on bad software, indicating that the accelerator issue was not caused by floor mats or a sticky accelerator pedal as Toyota claimed. Wozniak expressed frustration with his efforts to contact Toyota and the National Highway Traffic Safety Administration, highlighting a lack of responsiveness and communication regarding the software-related problem [595]. (b) Additionally, there are indications of accidental_decisions contributing to the failure. Owners of the Prius models reported that when they resumed cruise control, the car accelerated unexpectedly and resisted when they tried to brake, leading to dangerous situations. Some owners filed reports with the NHTSA but did not receive any response, suggesting a lack of follow-up on potential software-related issues. The dealership initially attributed the problem to floor mats, indicating a misdiagnosis of the root cause of the acceleration issue [595].
Capability (Incompetence/Accidental) development_incompetence (a) The software failure incident occurring due to development incompetence: - The software failure incident with the Toyota Prius was attributed to bad software by Steve Wozniak, the co-founder of Apple, who owned several Priuses, including a 2010 model [595]. - Wozniak expressed frustration with his efforts to contact Toyota and the National Highway Traffic Safety Administration, indicating a lack of responsiveness to the reported software issue [595]. (b) The software failure incident occurring accidentally: - The dealership that fixed the car for a Prius owner blamed the problem on floor mats initially, indicating a possible misdiagnosis or attempt to shift blame away from the software issue [595]. - Owners of the Prius models experiencing the software issue reported that the problem persisted even after the dealership blamed it on floor mats, suggesting an accidental misattribution of the root cause [595].
Duration temporary The software failure incident related to the Toyota Prius acceleration issue can be categorized as a temporary failure. The issue was reported to occur under a certain condition of cruise control, specifically when the "resume" button was pressed, causing the car to accelerate unexpectedly [595]. This indicates that the failure was not permanent but rather triggered by specific circumstances related to the cruise control system in the vehicle.
Behaviour crash, omission, other (a) crash: The software failure incident related to the Toyota Prius involved a crash behavior where the cruise control system caused the car to accelerate uncontrollably, leading to dangerous situations for the drivers. Owners reported instances where the car accelerated unexpectedly even when cruise control was engaged, and they had difficulty regaining control or stopping the vehicle [595]. (b) omission: The software failure incident also exhibited omission behavior as the cruise control system omitted to perform its intended function of maintaining a set speed. Instead, the system caused the car to accelerate beyond the set speed, disregarding the driver's input and leading to safety concerns [595]. (c) timing: There is no specific mention of timing-related failures in the software incident described in the articles. (d) value: The software failure incident did not involve a value-related failure where the system performed its intended functions incorrectly. (e) byzantine: The software failure incident did not display byzantine behavior with inconsistent responses or interactions. (f) other: The other behavior observed in the software failure incident was a failure to respond appropriately to driver inputs, leading to a lack of control over the vehicle's speed and posing safety risks for the drivers [595].

IoT System Layer

Layer Option Rationale
Perception None None
Communication None None
Application None None

Other Details

Category Option Rationale
Consequence no_consequence (a) death: People lost their lives due to the software failure - No information in the provided article suggests that people lost their lives due to the software failure incident. [595]
Domain transportation (a) The failed system was intended to support the transportation industry. The software failure incident was related to the cruise control system in Toyota Prius vehicles, which caused acceleration issues and erratic behavior while in cruise control mode, potentially endangering drivers and passengers [595].

Sources

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