Some 2013-2018 F-150 vehicles equipped with electronic shift on-the-fly (ESOF) 4-wheel drive (4WD) may exhibit an intermittent grinding noise while driving in 2-wheel drive (2WD) mode most commonly on acceleration. ESOF can be identified as it does not have a 4WD AUTO (4A) position on the mode selector switch (MSS). This may be due to a loss of vacuum to the integrated wheel end (IWE) actuators and/or wear of the IWE components. To correct the condition, follow the Service Procedure steps to reprogram the transfer case control module (TCCM) and replace any worn vacuum and/or IWE components.
