to check if the 4th axis option is enabled
press SYSTEM CONFIGURATION
press PURCHASED OPTIONS
page down and look at option 20 - 1ST ADDITIONAL AXIS. If it is marked as PERMANENT then you can use the axis.
all Arrows were wired to accept a 4th axis so all connections should be present, however it is probable that you will need a Kollmorgen 6 amp drive. check in the panel and see if there is a 4th axis drive present. standard machines have a power supply, spindle drive and 3 axis drives (x,y,z). for 4th axis you would need another drive.
e-mail me at email@example.com if any more questions