How do I install a more "modern" coolant temperature sensor?

The single wire is grounded by the body. For the two wire, one is for the existing and the other is for grounding to any part of the engine that has a good ground.

This is a thermister which would not short out.

However you must remember that a different version of the original would not work if the ratings are different.

It's made for my model vehicle, it's just got two wires instead of 1. So I just need to ground it to the engine block?

you really need the single wire connector but if it's unavailable actually a connector should have come with it because you won't have the right connector. if you don't have that you'll have to try to get one or the right switch. if you get the connector with a harness all you will need to do is put eh computer wire to the yellow wire and ground the black wire.

They are both black on the new sensor. The original single wire is black also.

then just wire it up it should work. gm changed to this type many years ago

So the extra wire goes to the engine block?

one wire to computer and one to wherever you wan tto ground it. engine block is fine

I don't think you understand. The old wire is still there. I cut the old connector off of that wire and spliced in 1 of the new wires. I now have an extra wire.

you don'tunderstand, put the remaining wire to ground. engine block is fine to use as a ground

lol, as I explained earlier, the original sensor uses the body as ground spo when the sensor is installed, it is automatically grounded.

For the two wire sensor, the wires are not in any way connected to the unit body. When it is installed, it is not grounded. The extra wire is the ground which you need to find a location for it.

I grounded the second wire as you said, it still isn't reading the temperature. It bounces around the falls all the way down to 260 and twitches. Any other suggestions? Ground is good, verified withe a multimeter. I'm at a loss, I usually always figure these problems out on my own.

coolant sensor is not for the temp gauge. that unit is on the left front head between the first 2 cylinders.

Roy

Yup, sending unit and ECT are two different thing. Disconnect the one that you have installed and note if the gauge works. This is to confirm if you are working at thr right place. The other thing is that you could have bought the wrong item, instead of sending unit you asked for temperature sensor.

teh temp sender is in the cylinder head normally the drivers side, ground the wire out and if the gauge goes to hot then it needs to be replaced.

So the sensor on the rear right of the block doesn't affect my guage, the one by the thermostat does?

Yes you are correct.

So is it the one under the TB just behind the Thermostat next to a small vacuum line?

It should be a one connector sending unit. Dis connect it and turn ignition switch on. If gauges does not work, ground the wire and check if the gauge goes up to max.

It goes up to make and twitches rapidly at max temp. I think it needs a new wire. I kept the original single wire just cut the connector off and spliced in the new one.