Engage 4X4 as per yr vehicle
e.g
1st) Free Hub Lock
2nd) 4X4 gear lever/button
Get under the vehicle & rotate front shaft if it does not the 4X4 is engaged
else not
For rear diff lock
Engage it as per ur vehicle
Then lift the rear 2 wheels on jack
Rotate any wheel the other should spin also
If not then Rear Diff is not locked
Regards