964 OBC testing?
 

I am trying to install a 964 Tach with OBC in my 914-6 3.2 conversion. I am bench testing it first. Connecting up the positive and ground, I can make all the idiot lights work. High beam, Turn signals, etc, but the OBC does not come on. Should it come on by just applying power or is there something else that needs to be connected first? Or is the OBC bad? Thanks in advance for the help!!