If your car is an '89 model, you'll have a 'sword' module. A fairly common problem that occurs is the failure of several mosfet transistors mounted on the 'sword' itself.Originally Posted by romus
However, because the variable speed control is working intermittantly the problem won't be caused by failed mosfet transistors. If they had failed the varispeed function wouldn't work at all. As Winfred said it could be a faulty relay. Another possiblity is fractured solder joints where the connector meets the printed circuit board.
Anyway mine had exactly the same symptoms as yours and this is how I tracked down the cause and fixed it.
Sword Module Repair
Shogun reposted my original thread on another forum.
I can't seem to find the original thread I posted on bimmer.info?
Good Luck!![]()