temp gauge is screwy after safc install

[nd240sx3]

ok i hooked up apexi safc yesterday and i am prettdy damn sure that all wires are correct but when my car hasent run all day and i go to start it the temp gauge automatically goes midway up and stays there whats that all abotu hope someone can help thanx

[carnal_c30]

did you choose a good ground?? what did you use?

[nd240sx3]

i thought the 2 ground wires got connected to the ecu