It shouldn't matter.
If they are polarity sensitive, use a DC digital voltmeter where they hook up (the circuit board connections); the black meter lead being negative & the red lead being positive. Turn on the switch & read the meter with the leads at the bulb connection points. If the meter reads +12VDC, the point the red lead is attached IS the 12V positive & the other negative. If the meter reads -12VDC, then your leads are reversed (red is connected to the negative & black is connected to the +12VDC terminal).
Hope that makes sense to you & it helps! B)