I recently found a Volvo brand oil gauge and sending unit in a junked 740 I pulled the engine from. I didn't look closely at the wiring when I took the gauge out of the car and cannot figure out where the positive lead goes to. It is a blue/red striped wire with both male and female spade clips on it. Does anyone know where it attaches. I tried the different contacts on the speedometer but it only pegs the needle.