How to? (5v output from ecu to trigger relay)

I have an ecu that has a 0-5v output. Not sure how many amps, or if it can trigger a relay directly.

What I'm trying to do is rig something up that will trigger when it senses a 5v signal. Which in turn triggers a 12v relay (by grounding the relay).

What's the best way of doing this?

Logic-level NFET. Put a snubber diode across the relay coil, too.