Using either a digital or analog ohm meter, place one lead on the terminal (grey wire) and place the other on a known good ground. Usually a spot on the body whee there is are metal. If the is any reading on the meter other than O.L or "infinity" then the wire is shorted to ground. The bypass method will ensure you have power to the pump and allow you to see if the engine will actually run. Once you verify it will run on the pump the you can make proper repairs to the circuit. Ive seen peoe chase their tails for weeks trying to figure out whats wrong with a wire when there was a mechanical issue with the car. Start there and lemme know if u have any questions.