I have a '79 450 SL. Dont know if it is the same, but my hazards and turn signals share the same flasher. Do your hazards works??? If not, then this might help........
If they do share the same one, the flasher should be part of the hazard switch. You need to remove the ashtray, the mount for the ashtray, take out the two screws that hold the wood console in place, the shift boot (rubber around gear selector), and carefully lift the front of the wood about half inch or so. Then slide the wood section back and it should be free. On the bottom of the hazard switch is the flasher.
I had the same problem, but my fix was just cleaning some corroded contacts.
I dont know if the flasher seperates from the switch.....Thats for you to figure out
79 450 SL 184K