The wiring loom runs around the whole car, basically its all the wires that run to the particular part that needs signals, and they peel off at certain places to the certain part.
My advice is to check the wiring loom in the boot. On the left hinge for breaks - this is an old problem with E34s. Remove the plastic covering and you may find one or more wires split or cut through completely. It happens over time. If you find nothing wrong here then pull the back seat and check the wiring loom on the right hand side (NZ driver's side) where it goes through a hole into the boot.
This happened on my uncles E34, but sometimes none of his lights would come on, e.t.c.
Hope it checks out.
<a href='http://www.photobox.co.uk/album/1118083' target='_blank'>Check out my ride!!!</a>
<div class='quotetop'>QUOTE</div><div class='quotemain'>(From Family Guy) Brian to peter: Well peter you've only got a couple hours left. If your gonna pull a party outta your ass you might wanna stand up!</div>