As root, verify that the kernel module is loaded.
For example, to verify the u8lat1 is loaded, you would type:
system# modinfo | grep u8lat1 89 ff798000 4b13 18 1 u8lat1 (UTF-8 <--> ISO 8859-1 module)
Use the modunload(1M) command to unload the kernel.
For example, to unload the u8lat1 module, you would type:
system# modunload -i 89