EA19001 · Electrical Overstress
Opened Apr 19, 2019 · Closed Sep 19, 2024
Status: closed (inferred from source dates) · Air Bags: Air Bag/restraint Control Module
The Office of Defects Investigation (ODI) opened this investigation to determine if the failure of airbags to deploy during severe crashes, in certain vehicles, was the result of a safety related defect. During the investigation a complex failure was studied that can result in non-deployment of subject vehicle air bags and other restraint system devices in severe crash events. The subject vehicles may be equipped with an airbag control unit (ACU) for the supplemental restraint system (SRS) Electronic Control Unit (ECU) manufactured by ZF-TRW. The ECU receives signals from crash sensors mounted in the vehicle and deploys the vehicle air bags and seat belt pretensioners in accordance with manufacturer design specifications. The ECU in the subject vehicles contains a model DS84 application-specific integrated circuit (ASIC) which controls the communication of the crash sensor signal, firing commands (i.e., when to deploy the airbag(s) and/or pretensioners), and fault information (e.g., diagnostic trouble codes). In September 2016, FCA announced recall 16V-668 for certain model year (MY) 2010 to 2014 Chrysler, Dodge and Jeep products manufactured with the subject ZF-TRW ACU. In this recall, FCA discussed an EOS condition that resulted in a failure of the subject DS84 ASIC, which caused air bag non-deployment. FCA noted that the defect condition had only been observed in vehicles equipped with sensor harnessing routed across the front of the vehicle. Other FCA vehicles that also used the subject ACU, but were not equipped with cross-car harnessing, had not experienced EOS failures, despite similar time in service. During the course of this investigation, ODI sent two separate Information Request (IR) letters to six vehicle manufactures (including FCA, Hyundai, Honda, Kia, Mitsubishi, and Toyota) and one IR letter to ZF-TRW. These IR letters resulted in ODI receiving comprehensive data from these manufacturers and suppliers. Studies of this data found that the DS84 ASIC does not have sufficient protection against negative electrical transients or electrical overstress (“EOS”) that can be generated in certain severe crashes. An electrical transient occurs when the electrical power supplied to a circuit changes momentarily over a short duration of time. In these severe crash cases, the crash sensors and other powered wiring can be damaged and short circuited so as to create a negative electrical transient of sufficient intensity and duration (that are outside the vehicle manufacturer's specification) to damage the ASIC before the restraint device deployment signal is received by the SRS ECU. This damaged signal can lead to incomplete or nondeployment of the air bags and/or pretensioners. Airbag non-deployment and/or lack of pretensioner operation can increase the risk or severity of injury in a crash.A total of 8 fatalities and 14 injuries were associated with known EOS events. The common element in all investigated manufacturers vehicles is the SRS ECU containing a DS84 ASIC manufactured by ZF-TRW. The risk associated with the ASIC is equally shared among all OEMS involved in the investigation. The actual real-world risk can be mitigated by other factors which were assessed by ODI during this investigation. The first mitigating factor involves protections built into the ACU design which protect the DS84 ASIC from damage. There are multiple strategies and levels of protection employed by different OEMs that provide effective EOS mitigation. The two most common strategies at the ACU level are circuit protection diodes on the remote senor signal lines, and current limiting resistors that protect critical components. The second mitigating factor is found at the vehicle level and involves the location and routing of the wires leading from the crash sensors to the SRS ECU. If the wires are well protected in a crash and are not routed with other power wires carrying large currents, the risk for an EOS event is significantly reduced or eliminated. These design specific factors combine to produce a spectrum of risk for the vehicles equipped with ACUs using the DS84 ASIC. Given the many of years of field exposure, it is possible to divide the subject population into two groups; vehicles which have experienced EOS events, and vehicles which have not experienced EOS field events. Four of the six OEMs involved in this investigation have experienced EOS field events on at least one of their models equipped with a DS84 ASIC. All vehicle models (including the Toyota models identified in the Failure Report Summary of the opening resume for this investigation) with field events have been recalled. In an abundance of caution, ODI kept this investigation open five years to monitor field performance and did not identify any field events on vehicles not included in existing safety recalls. Given the spectrum of risk identified in this investigation and that all vehicles with a demonstrated unreasonable risk have been recalled, ODI is closing this investigation. ODI is closing this investigation with the following manufacturer safety recalls: 16V-668, 18E-043, 18V-137, 18V-363, and 20V-024. With the recall actions taken by the subject vehicle and equipment manufacturers, this investigation is closed. The closing of this investigation does not constitute a finding by NHTSA that a safety-related defect does not exists on other model or model year vehicles outside of the recall scopes. The agency reserves the right to take further action if warranted by the circumstances.
DP14004 · Totally Integrated Power Module Failure
Opened Sep 25, 2014 · Closed Jul 24, 2015
Status: closed (inferred from source dates) · Electrical System
In a letter dated August 21, 2014, the Center for Auto Safety (CAS) petitioned the National Highway Traffic Safety Administration (NHTSA) to initiate a defect investigation of alleged failures associated with the Totally Integrated Power Module (TIPM) installed in Chrysler SUV?s, trucks, and vans beginning in the 2007 model year. The petitioner alleges that TIPM defects may result in engine stall, airbag non-deployment, failure of fuel pump shutoff resulting in unintended acceleration, fire, and other symptoms. On September 25, 2014, the Office of Defects Investigation (ODI) opened DP14-004 to evaluate the petition for a grant or deny decision. ODI analyzed complaint data provided by CAS as well as complaints submitted to ODI from consumers. In total, there were 296 complaints submitted by the petitioner in the original petition and five supplements, including 271 complaints related to the subject vehicles equipped with TIPM-7. Approximately 3 percent of CAS complaints are related to vehicles equipped with TIPM-6 and ODI?s review of these complaints did not identify any safety defect trends. ODI conducted a detailed review of complaints narratives submitted by CAS and consumers including careful analysis of vehicle repair histories, warranty claims obtained from the manufacturer and any available Customer Assistance Inquiry reports (CAIR). Analysis of the field data indicated that MY2011-2013 Jeep Grand Cherokee and Dodge Durango vehicles exhibited significantly higher complaint rates related to fuel pump relay (FPR) failures than other subject vehicles. In a September 3, 2014 letter to NHTSA, Chrysler submitted a Defect Information Report (DIR) identifying a defect in the FPR within the TIPM-7 which can result in a no start or stall condition in approximately 188,723 model year (MY) 2011 Jeep Grand Cherokee (WK) and Dodge Durango (WD) vehicles manufactured from January 5, 2010 through July 20, 2011 (14V-530).In a February 24, 2015 letter, Chrysler submitted a second DIR expanding the scope of the FPR defect condition to include an additional 338,216 MY 2012 through 2013 Jeep Grand Cherokee vehicles manufactured from September 17, 2010 through August 19, 2013 and MY 2012 through 2013 Dodge Durango vehicles manufactured from January 18, 2011 through August 19, 2013 (15V-115).ODI analysis of the CAS allegations of TIPM defects resulting in stall while driving, airbag non-deployment, unintended acceleration, fire and other faults identified a single defect condition related to 1 of over 60 different circuits in the TIPM assembly. The most common effect of this defect condition, related to the fuel pump relay, was a no-start concern, but it could also result in stall while driving (76 complaints). No valid evidence was presented in support of claims related to airbag non-deployment, unintended acceleration or fire resulting from TIPM faults and these claims were found to be wholly without merit based on review of the field data and design of the relevant systems and components.Except insofar as the petitioner's contentions relate to the defect condition addressed by the Chrysler recalls, the factual bases of the petitioner's contentions that any further investigation is necessary are unsupported. In our view, additional investigation is unlikely to result in a finding that a defect related to motor vehicle safety exists or a NHTSA order for the notification and remedy of a safety-related defect as alleged by the petitioner at the conclusion of the requested investigation. Therefore, in view of the need to allocate and prioritize NHTSA's limited resources to best accomplish the agency's safety mission, the petition is den
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