|September 3, 2010 - I do love my bead blaster.|
This is a relay for the starter solenoid - probably added to the MG over the course of production to protect the poor ignition switch from the power needed to trigger the solenoid. The Miata switch is robust enough to handle it, but the wiring in the MG harness is a little smaller than I'd prefer. So I'll keep my relay to trigger my solenoid to trigger my starter. At least, that's how I'm thinking now.
Just look at what 20 seconds in the bead blasting cabinet did to this (probably) 38-year-old component. There's no corrosion on those contacts!