I had this problem on my old Mk1 325i Sport. It was caused by a fuse wire within the relay blowing. Fortunately it is easy to fix. From memory, the relay (small aluminium box) is located under the dashboard behind the glove box. If you remove the check straps you should be able to drop the glovebox ...

My '87 Mtech 1 is now for sale. See the post in Cars for Sale section......