I've recently acquired an oil pressure gauge, specifically this one:

eBay - The UK's Online Marketplace

but it unfortunately came without wiring instructions. It has three terminals, which someone has hand labeled in marker pen, as + on one side, I (or maybe H) in the middle, and S on the other side.

+ is presumably switched live, would S be the sender and the other one earth? I would experiment, but will I blow it up if I connect it wrong?

cheers

what colour are the wires, i would have expected a red (switched +12v) a black (neg) and another which would goto the sender?

Sadly no wires, just a gauge which is unlabelled apart from the hand-drawn labels. I'll probably just give it a try with S as the sender.