door lights

i am going to wire a LED strip to the door lights so it comes on when i open the door, which wire is positive and which wire is negative

Do you have a Voltmeter or Multimeter?

Hook up the Red and Black leads of the meter to each wire.
If you get a positive voltage reading then the Wire on the red lead is positive and wire on the Black lead is negative.
If you get a negative voltage reading then the Wire on the red lead is negative and wire on the Black lead is positive.

Hope this helps.

Do you have a Voltmeter or Multimeter?

Hook up the Red and Black leads of the meter to each wire.
If you get a positive voltage reading then the Wire on the red lead is positive and wire on the Black lead is negative.
If you get a negative voltage reading then the Wire on the red lead is negative and wire on the Black lead is positive.

Hope this helps.

i dont have a volt meter but starting to think i should get one. how much do they run?