It's a bit like a fuel pump relay output. For safety/security.

Unless the ecu is in place, or possibly detects a crank signal, it will not energise and allow fuel to be pumped.
So the ecu controls this, and will ground the relay to allow full operation. If you test this output with a voltmeter and get 12v, that is perfectly normal in it's safe state. Rather than having no earth connection. They simply apply 12v to the coil instead. 12v to both sides = no potential difference so the relay will never energise.