EA21001 · Loss Of Direction Control
Opened May 6, 2021 · Closed Aug 25, 2023
Status: closed (inferred from source dates) · Steering
On May 6, 2021, the Office of Defects Investigation (ODI) opened Engineering Analysis (EA21-001) to assess a sudden loss of steering control, in Model Year (MY) 2013-2015 Honda Accord vehicles. Consumers alleged while driving the steering wheel would pull to the left or the right independently. Steering pull may pose a risk of loss of directional control. Honda stated that they believed the inadvertent steering input was caused by a loose magnet located within the electronic power steering (EPS) system. Due to poor formulation of the adhesive, this magnet can become loose and move up to 2 degrees around the steering column. When the magnet moves, the torque sensor generates a signal that results in unwanted steering in either direction. Honda stated the steering force required to maintain directional control with a loose magnet is a maximum of 3-pound feet. The maximum force of the unwanted steering input can be overcome by the driver and is similar to driving on grooved pavement.The Vehicle Research Test Center (VRTC) sent over 4,000 questionnaires to 2013-2015 Honda Accord vehicle owners. Of the 637 responses, 58 consumers experienced unwanted steering. Consumers experiencing unwanted steering did not report difficulties maintaining directional control. There were no crashes or injuries reported to VRTC. Testing done by VRTC was not able to reproduce the allegations. Analysis of all relevant data indicates that the subject condition has a relatively low failure rate. The poor adhesive formulation was addressed by the supplier with three (3) counter measures in the manufacturing process.There has been a declining trend in consumer complaints to NHTSA which indicates possible exhaustion of parts prone to failure. In view of the low rate, declining complaint trend, the nature of failure, and resolution of the adhesive formulation, this Engineering Analysis is closed. The closing of this investigation does not constitute a finding by NHTSA that a safety-related defect does not exist. The agency reserves the right to take additional action if warranted by new circumstances.The ODI complaints cited above can be viewed at www.NHTSA.gov under the following ODI identification numbers: 11538714, 11528538, 11528008, 11522953, 11496557, 11495837, 11494328, 11478680, 11477167, 11476758, 11476263, 11471198, 11470001, 11467026, 11466561, 11466016, 11465626, 11464143, 11463558, 11462759, 11461500, 11460777, 11460191, 11455540, 11454334, 11452198, 11448114, 11447666, 11444888, 11444823, 11444172, 11443324, 11443243, 11443105, 11441374, 11439520, 11438345, 11437261, 11436824, 11436350, 11435994, 11435079, 11434969, 11434545, 11434442, 11434381, 11433824, 11433745, 11433555, 11433368, 11433176, 11431206, 11430465, 11430253, 11430009, 11429253, 11428301, 11427449, 11426841, 11426340, 11425928, 11425261, 11425230, 11423611, 11423245, 11422445, 11422395, 11422351, 11422220, 11422138, 11422069, 11421683, 11421589, 11421540, 11420573, 11419338, 11419270, 11418147, 11418143, 11417768, 11417742, 11417570, 11417437, 11416804, 11416699, 11416401, 11416378, 11416375, 11416155, 11416117, 11416084, 11416051, 11416032, 11416028, 11416024, 11416000, 11415933, 11415915, 11414105, 11406220, 11398736 ,11387075, 11387049, 11375580, 11364698, 11361125, 11351660, 11349961, 11327909, 11327170, 11301957, 11289067, 11282525, 11277659, 11258017, 11256914, 11218752, 11208077, 11196050, 11194358, 11189901, 11165075, 11163481, 11154891
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.
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