Outer Limits 4x4 Board

hey guys, my missus dad has a factory diff lock on his SWB GQ, but when you engadge it it takes ages to kick in, then when it does kick in it takes twece as long for it to disengadge. is there a reasonf for this? a speed he has to pass? a rev limit?

The factory solenoid on the passenger side fire wall that engages the diff lock is not all that good. If it gets a bit of use it is worth his while sourcing an aftermarket alternative..