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It appears that your ECT may be two in one; a sensor and a sender.
Not sure; you will need to check and see how many wires it has, etc.
ECT sender - works the gauge -
ECT sensor - goes to the computer for emissions, fuel, etc.
If you have more than two wires, I bet your sensor does both and sends the signal both ways. Totally unsure though; I'm a Ford guy.