electrical probl;ems

we have a 1996 diesel jetta that seems to lately have strange things
happening with the electrical systems involving mostly the radio, the
alarm system and the power door locks as well as the cruise control.
the radio goes into safe mode after the doors are locked and the alarm
goes off
the alarm goes off after the doors are locked with the keys in either
front door and the the back doors or trunk is closed
the doors will not always lock and will not always lock from the inside
switch
and the cruise control works only every once and a while . this was the
first problem we had and the others have slowly developed over the last
2 months

does anyone have any suggestions as where to look i have not checked any
of the electrical sysytem yet but i am going to check the battery and
ground and check the fuse and relay panel for any loose fuses and or
relays any other isdeas . i will check anything that anyone suggests
..or if anyone has a web site that may haelp

thanks in advance

john harrison

73 westy
91 jetta
96 jetta
75 bettle (restore project)