can anyone tell me what this relay does?
 

Yes
 

Mercedes Benz Bosch Turn Signal Relay.

More data:
Part # 150331 P2020-13252 Bosch Mercedes Turn Signal Relay Fits Year: 1972 - 1976
Model: Mercedes 280C Engine: 110.921 Chassis: 114.073

Category: Bosch Turn Signal Relay > Mercedes Turn Signal Relay > Mercedes 280C Turn Signal Relay

Part # 171673 P2020-13252 Bosch Mercedes Turn Signal Relay Fits Year: 1972 - 1972
Model: Mercedes 350SL Engine: 117.982 Chassis: 107.044

Category: Bosch Turn Signal Relay > Mercedes Turn Signal Relay > Mercedes 350SL Turn Signal Relay

Part # 179623 P2020-13252 Bosch Mercedes Turn Signal Relay Fits Year: 1976 - 1980
Model: Mercedes 450SEL Engine: 117.986 Chassis: 116.033

Category: Bosch Turn Signal Relay > Mercedes Turn Signal Relay > Mercedes 450SEL Turn Signal Relay


Part # 180979 P2020-13252 Bosch Mercedes Turn Signal Relay Fits Year: 1976 - 1980
Model: Mercedes 450SL Engine: 117.985 Chassis: 107.044 Chassis Up To: 043357

California
Category: Bosch Turn Signal Relay > Mercedes Turn Signal Relay > Mercedes 450SL Turn Signal Relay

Part # 263869 P2020-13252 Bosch Mercedes Benz Turn Signal Relay Fits Year: 1974 - 1976
Model: Mercedes Benz 240D Engine: 616.916 Chassis: 115.117

Category: Bosch Turn Signal Relay > Mercedes Benz Turn Signal Relay > Mercedes Benz 240 Turn Signal Relay

Yep, what Whunter said.

For the price of these things, I pull them at junkyards as often as I can!

thanks,i found it when stripping the old sd.