Brake Fluid Warning light and PWDA

1991 110, 200 tdi which only has the PDWA operated light (Pressure Differential Pressure differential warning actuator, situated on bulkhead). Have fitted new Brake Master Cylinder today which has the fluid level sensor and yellow switch on the cap. I don't have any electrics on for this. I am assuming one is live and one is earth, so question is, if I take a live off the PWDA and then earth the other, I will have a brake warning light actuated by both the PWDA and the fluid level indicator?

Also, is there an actual plug that fits into the yellow fluid level indicator (as shown ) or just two spade connectors? If plug, where can I get one!

Two spade connectors, one with a black earth and one with two black wires with a white(grey?) trace - on mine anyway. The connectors are probably tucked away inside the loom on the engine side.