hi i have a vitara when i put it in 4wd it makes a bang then slips back into
2wd so it will not stay in 4wd any body know what it my be

when i put it in 4wd 30 seconds latter you here a bang from the back and it jumps back into 2wd, so it will not stay in 4wd i have a vitara 1990 . can anyone help to what it may be , thank you mike