I know on the XL2 (after having issues getting mine TO work), it turns out that there are switches inline with the solenoid that if the door-latch is pulled, it opens the solenoid releasing the air lock.

Even more on the XL2, the solenoid will not engage unless the parking break is in the OFF position.

When parked there is a door lock button, but it simply engages the regular door latch, not the air latch.

Ray