Hmmm, nevermind, on zooming the picture I can see it's NOT a typical Bosch relay.
Got a bigger picture than that?
Anyway, like Catalin says, the two pins showing a slight resistance will be your coil; the other two will be the normally-open contacts.
You know, the standard Bosch relays can be had for
$6 or so at Princess Auto... why not just pick one up and follow the standard wiring diagrams available for it all over the web?