Any electronics experts in the house?

[89Vette]

By 12v high point source, they just mean a positive 12V. They are saying ANY 12v source you can splice into will trigger the relay if it's a switchable power supply like the radio.

If you have a 12V probe or volt-ohm meter, just look for a connector that turns on/off when the key turns on. If this system is worth a crap, you'll only be pulling a small amount of juice to trigger a relay (meaning you won't need to increase the fuse on that circuit).

[Gussie2000]

You can try running the last wire to the cigarrete lighter since this one runs 12v as soon the car's ignition is in "on" position.

[psychos2]

Get an oil pressure sender that works as a switch and install near the oil filter and wire to that.they are normally used to turn on electric fuel pumps . shawn