You can tell if you have the solenoid to electrically lock the brakes out by looking for the brass thing at the rear of the coupler's master cylinder:


That brass thing is the solenoid.

Mine came from the factory with a bad ground wire that made the lockout non-functional. I tightened the screw holding the ground wire to the one of those two tapped holes you see in the base of the solenoid and it's worked perfectly since then!