Connecting to a floating pin that gets ground.

So I want to read a relay state in an automotive application and that relay is controlled by a ground. The other side of the coil has 12v battery applied to it, if I connect to the ground side of the relay thats not switched on wouldnt that ground side be floating at +12v through the coil? is there a good way to bring this down so I dont damage my arduino? would a resistor divider circuit work?

reverse biased diode …cathode (banded end) to relay switch , the anode to Arduino pin with maybe a O.1 uF cap to absorb any glitches.

s10mods:
So I want to read a relay state in an automotive application and that relay is controlled by a ground. The other side of the coil has 12v battery applied to it, if I connect to the ground side of the relay thats not switched on wouldnt that ground side be floating at +12v through the coil? is there a good way to bring this down so I dont damage my arduino? would a resistor divider circuit work?

Put an opto isolator across your existing relay ( obviously using an appropriate resistor for the internal diode/led)

Then use the open collector opto output with say a 10K resistor to your 5V rail ( assuming a 5V arduino) with the
10K resistor ...collector junction point as your Arduino input and the emitter to your Arduino ground.opto.jpg%201.jpg

opto.jpg%201.jpg