The sender only needs one connection to the car's loom. The goes low (to ground) when the pressure is low so the other pin is not needed unless the sensor features another connection either a dummy or not used on your car. The last M30 sensor I swapped from a non OEM source had one pin, looking at it from the front with the notch upwards the pin too the right is the car's loom pin.
With the ignition off ground the wire from the loom to the block (you wont breeak anything) then the light should stay on. Turn on and off the ign, you should not get any gong's. If that works then remove the wire from the block and then try the same test the light should stay off. If so then the wiring etc is ok. Next step check out the sensor it might be the wrong one. It is a simple power->bulb->switch->ground setup you should not need anything else.
The wiring is brown/green for the sender. Anywhere under .5 BAR should bring the light on FYI.
HTH
Steve