I just replaced the alternator on my 84' 190D. It was a genuine rebuilt Bosch alternator and everything went fine. Car runs great. First time my wife drove it to town, she came back and told me the turn signals did not work. The turn signals have always worked on this car. I checked all the fuses. None were blown. Does anyone have any ideas what to check next and could the new alternator have caused this? Thanks.

 

Check the fuses again. It's not that they're blown, just likely not making good contact.

 

Flasher. I'm not sure where it is on your rig, but on the 83 300D it's under the ashtray. Not directly under it, but you have to remove it along with it's bracket, then you have to lift the top part of the console up. Easy job.

 

Sometimes its a small hair line crack in the copper blade that prevents it to make a good contact.Make sure you replace it with a porcelain fuse.
I do have a question for you....Was the battery voltage low before replacing the alternator?
I have seen many of times people replacing a defective alternator and having a low voltage on the battery,but not charging it before firing the engine up.This can cause diodes in the alternator to go short and sometimes can create havoc in the electrical system.
Good luck
Cheers