Just swapped, put on ACC/ON position, temp gauge maxed on hot?

[Indolent]

-rb26dett-koyo aluminum-e-fan's aren't wired up/working yet-swapped ka temp sensor (single pin) with the rb temp sensor-blue/black wire wired up to cluster/dash harness, from the ecu it's spliced in a 3 way (temp sensor to ecu/dash harness plug)

just swapped my rb in, car turns on/works fine and everything but..when i turn the key on the ON/ACC position the temp gauge needle shoots up to all the way Hot? I don't understand why it's doing so when i never ran the motor on in the first place

i tried driving around like for a couple minutes or so, i don't remember if i did anything or turned the car off then turned it back on but all of a sudden the temp gauge seemed to work, it was near the middleish then as i drove it seemed to go down and kinda move but i didn't drive around much like that

i tried directly connecting it to the dash harness plug by cutting off the part of the 3 way which goes to the ecu, this time it didn't shoot all the way up, so i thought maybe it was working? i drove around for a couple minutes but the temp gauge didn't seem to budge or does it just take forever to get to normal operating temp?

Now i'm wondering what i left out or whats wrong, any suggestions?

[Joe]

the ecu has its own temp sensor (the 2 pin plug right next to the 1 pin one you switched), you dont need to splice into the ecu's temp sensor wiring, that is why it was shooting to hot.

yes it takes a while for the engine to start to warm up.