To enable erlang autocompletion in vim, you'll need to get a dictionary with the Erlang keywords first. There's a file available at: erlang.dict.

Save erlang.dict to the folder ~/.vim/dict (or any folder you wish, just keep it consistent... create if necessary).

Then add to ~/.vim/after/ftplugin/erlang.vim (create if necessary):

setlocal softtabstop=2
setlocal shiftwidth=2
setlocal tabstop=2

setlocal iskeyword+=:
setlocal complete=.,w,b,u,t,i,k
setlocal dictionary=~/.vim/dict/erlang.dict

setlocal makeprg=erlc\ %

That's it.

Now type lists:, press <Ctrl> + p in edit mode (of an erlang file of course) and you should see the autocompletion.