This Preliminary Information communication provides information to the technician about vehicles that have a service four wheel drive message displayed in the driver?s information center. Technician may find Diagnostic Trouble Code C0387. Technician should follow published Service Information diagnostics for the Diagnostic Trouble Code if it is a current code. Technician will need to attempt to duplicate the concern if the Diagnostic Trouble Code is set history. If the customer experiences repeat occurrences of this condition and a root cause cannot be determined, it is probable that the transfer case encoder motor is not responding quickly enough and should be replaced.