NHTSA Engineering Analysis EA18001

On April 18, 2018, the Office of Defects Investigation (ODI) opened Engineering Analysis (EA) 18-001 to investigate reports of braking concerns in model year (MY) 2009 Nissan Murano vehicles. A failure of the hydraulic control unit (HCU) portion of the antilock brake system (ABS), which involves improper operation of an internal hydraulic control valve(s), can cause extended brake pedal travel and may result in a reduction in overall braking effectiveness. Tier-one supplier Continental manufactured the HCU for Nissan.The corrosion-preventive, zinc coating used on the armatures of the normally closed (NC) valves within ABS HCU may react with brake fluids lacking sufficient corrosion-preventative additives. This reaction can cause the formation of a gelatinous material, which may cause the NC valves to close slowly. Over time, the gel can solidify to an extent such that the spring used to return the valve to the closed position may not be able to overcome the gel buildup, allowing the NC valve to remain open. If any of the four NC valves remains open, fluid will be diverted to one or two accumulator(s). This misdirected fluid has the net effect of causing brake pedal travel to increase, however enough stroke remains in the pedal to generate braking force. Although the hydraulic braking system remains intact and full braking force is maintained once the pedal travels the additional distance, when this condition occurs, the initial increase in brake pedal travel could result in increased stopping distance. An existing Nissan Service Campaign was launched for MY 2009 vehicles built prior to 11/1/2007. After consultation with ODI as part of EA18-001, Nissan decided to expand this population to the full range of MY2009 Murano vehicles. Later Murano vehicles exhibit significantly lower rates of malfunction.During this investigation 156 complaints were identified that related to the braking concern. Within the complainants 2 allege crashes with 4 injuries. The Nissan reports