Looking for an electric relay adapter fitting

[Zebrafive]

I would release the terminal you need to tap into from the relay connector. Go to any auto electrical shop and buy a replacement connector.
From it make an adapter. A 1/4" male should plug into the connector you released from your relay connector. Just shrink wrap or tape it. Crimp the new connector onto two wires, one for connecting to removed wire, one for new circuit.

 

[Bladehauler]

You might get a relay harness with the pigtails and sacrifice an old relay to make the male end of your plug, just take the case off , drill a hole for your pigtails to pass through, remove the coil and contacts and solder your pigtails to the remaining contacts .seems like the way to keep from cutting your factory harness.