From The E28 Wiki
By Tjn182, Wed Mar 01, 2006
Original thread: Turn signals don't work, but hazards do! What gives?
Problem: My turn signals don't work, but my hazards do! What gives?
Cause: 1) Busted signal switch (lever) - worn out and in need of replacement, or 2) Fuse 11 is bad.
Solution: 1) Order a new turn signal lever (make sure you specifiy if you have the ability to switch ECU functions via the lever). It's a simple removal of the steering column, unscrew old part, screw in new part; or, 2) Check and/or replace Fuse 11.
If neither your turn signals nor your hazards work - then your problem is with the turn signal relay - a universal part, located in the steering column as well.
