How to connect 9Vdc GPS to Arduino Uno 5Vdc

I just got my first Arduino board so I am new at this.

I have a Garmin 15xH-W OEM GPS receiver requiring 8Vdc to 40Vdc unregulated which I want to connect to Arduino Uno. I want to use 3 wires from the GPS, Red for Volts, Black for Gnd and Gray for the one second pulse. Uno only gives me 5V, so if I connect the Garmin to a 12Vdc supply, how do I connect Gnd to common for the GPS and the Uno?

With the power solved? how do I capture the pulse per second? Set a digital pin to output and read in a loop? I was not able to try this since I do not have a pulse yet.

The purpose is to count the 1 second pulses and then once every minute execute a new routine which will energize a relay and some more code after that. The relay requires 12Vdc to energize, so the same Common Gnd problem?

Your help will be appreciated very much.

http://www.garmin.cz/files/documents/gps15xh_15xl_techspec.pdf

if you read datasheet carefully electrical charactristic

you can give 3.3v to 5v as lower voltage.

if you want toi give 9v use 7809 regulator IC . output both can use to turn on GPS & controller(Vin pin)

Thanks AMPS-N

You put me on the right track. I now see that I can power the GPS from the Vin and Gnd pins. I tried it and it works, I get the 1 second pulse which I need :)

Now to get the program to work.

Thanks again.