What @RaKid said.
most are just a coil inside to make an electro magnet, since it is pulling a bit of metal and not another magnet the polarity won’t matter.
some are but then the wires are coloured, marked in writing or unit will be marked.
MAC ones are all black.
the only ‘guide’ I’ve seen is to do with which side the switching is on. The ground lead should be switched which is what ECU’s and boost controllers do. Unless it’s USA v8 based stuff then some have switched positive and switched negative to choose from.