coolant temperature sensor problem

My old '95 has been sitting for about a year because of a blown brake line. I finally had it fixed, but when I started it up and it ran fine for about two minutes, then went into "limp home" mode and the dashboard computer read Engine Hot Turn off car. The temperature gauge was pinned, but the engine was still cool enough to touch. My traction control and abs dummy lights are also on.

I removed the engine coolant temperature sensor and it ran fine. Okay, problem solved right? I replaced the part and now the car does the same thing, but even faster...like 20 seconds after I start it. I replaced the thermostat just for fun, but no change. Is my computer shot or I am just missing something here?

With the CTS unplugged and the key on, what voltage is on the yellow wire? With the connector plugged in and the key on, what is the voltage on the yellow wire? With the engine running, the connector plugged in, what is the voltage on the yellow wire? Because the ground is a shared circuit, one of the other circuits could be causing an issue.

The computer expects to see voltage drop on that wire as the engine warms-up. If the voltage stays high or low, it can cause a problem and the computer should set a code. Things that can cause a problem, faulty sensor--faulty ref voltage--faulty ground, the ground circuit is a shared circuit. Cooling system problems could cause an issue.