Mercury Defect Investigation DP15001: Loss of power steering while driving
2011 Mercury Mariner Hybrid
Loss of power steering while driving
Steering:Electric Power Assist System
- Summary
- On May 27, 2014, amended June 2, 2014, Ford Motor Company (Ford) submitted a Defect Information Report (DIR) to NHTSA describing a safety defect that may result in a sudden loss of power steering assist while driving in approximately 746,067 model year (MY) 2008 through 2011 Ford Escape vehicles equipped with electric power assisted steering (NHTSA 14V-284, Ford 14S05). Ford's DIR described the defect condition as a poor signal to noise ratio [SNR] in the torque sensor within the Electric Power Assisted Steering (EPAS) system [which] does not allow the PSCM to determine the driver's steering input. When the system detects this fault condition, it transitions the EPAS system to the fail-safe/manual steering mode.Ford's DIR indicates that loss of power steering assist while driving would require higher steering effort at lower vehicle speeds, which may result in an increased risk of a crash.Ford's remedy instructs dealers to check the Power Steering Control Module (PSCM) for Diagnostic Trouble Codes (DTCs) to determine the proper repair procedure. If no DTCs are present, dealers are to update the PSCM and instrument cluster module software. The updated PSCM software changes the torque sensor fault strategy so that the SNR condition does not result in a loss of power steering assist while driving.In addition, audible and visual warnings are provided for torque sensor faults.If DTCs indicating faults in the torque sensor, PSCM or Power Steering Motor (motor) are present in the initial recall inspection, the dealer performs the following repairs: 1) replaces the torque sensor for torque sensor faults (DTC B2278); or 2) replaces the steering column for faults related to the PSCM (DTC B1342) or motor (DTC B2277).Continued in attachment pages
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