Ah, negative side to the sender. Great, thanks. That makes it easy to figure out which is the positive and which is the negative, then, since my diagram does show me which wire goes to the unit.
Now...after a friend and I looked up some electical diagram things online, it looks like one of the symbols between the gauge and the sending unit is a resistor? There are also two other symbols I haven't identified yet...but is it safe to connect a wire straight from the gauge to the sending unit?
