First time here guys and I desperately need help.. I have a 93 accord 5 speed and I'm working through some problems the previous owner handed down, currently and the most frustrating is when I have the key on the 3rd turn nothing will light up or get power, I can press the brake pedal, sometimes it takes several pumps, and everything comes up and the car will start but as soon as I touch the brake pedal everything loses power and the engine dies... plz help its a great car but it's all I have and I'm at my wits end

 

Plz help, my 93 accord 5 speed doesnt get any power to anything with the key on the 3rd turn but when I press the brake pedal I get power,note that sometimes it takes a lot more than one press of the brake pedal, but once I get power the car will start and run great, but once I touch the brakes everything loses power and the engine dies.. I've changed the main relay and now I'm stuck I'm no everyday mechanic but the brake pedal acting as a killswitch is baffling

 

Lets start with the simple things first.

Be sure all ends of both battery cables are clean and tight.