96 lumina temp gauge not working help!

i just bought a 96 lumina a few weeks ago and the temp gauge doesnt work and the cooling fans run all the time.i replaced the engine cooling temp sensor by the thermostat and still nothing.i grounded the green wire and gauge does nothing.is there a possible blown fuse somewhere ? and also looks like on back of block drivers side (3.1) there seems to be a sensor broke off but i cant find any wire or harness to plug anything into it.one website said the cooling temp sensor also runs the gauge while another said there is a seperate sensor for the gauge.any ideas??

I'm not sure that I'm right but I recall that the temperature sensor that sends the information to the dashboard and the one that switches the fans on are two different units. Check the circuit diagram in the repair manual.

I had very similar symptoms and I replaced the thermostat, it turned out to be stuck even though it wasn't very old (~6 months).

I was getting a check engine light, the code for which indicated coolant temp below t-stat operating temperature. You may want to check to see if you are throwing codes.

The CTS on your '96 is a two-wire sensor with a yellow and a black wire. The sensor for the instrument cluster uses a dark green and a black wire. I'm guessing the wrong one was identified. Before you condemn the sensor, make sure the problem is not the wire harness. Test the resistance ot the CTS. It should be close to the following table:

http://72.19.213.157/files/CTSMAT.gif

do the fans run even when you turn the car off?

looks like i have a sensor broke behind engine on drivers side that i thought could be the sensor for gauge,but not sure where it would plug into,i seen a sensor on the advance auto parts web site but plug for it looks completley different then anything i have under the hood

no,just as soon as you turn on the key they come on,i read something about it where if the sensors arent working it will run in a safe loop mode so maybe thats why they are on.car seems to run cool after a hour drive you can put your hand on the upper intake and its warm but not hot.

where would the sensor for the gauge be located?i have heard 2 different things one saying the coolent temp sensor that i replaced close to the thermostat runs fans and gauge,that code was coming up and i seen a gauge sending unit on the advance auto parts website but wire for it looks to be one black wire and i cant find any un used harness to even plug it into.there is 3 close to the alternator that are unplugged but dont look anything like what that plug looks like on the website.....

On my '96, the CTS is a 3-wire sensor mounted forward (toward the right on a wrong-wheel-drive) of the thermostat housing.

http://mysite.verizon.net/strey/files/1996-191CTSLocation.jpg

The single sensor is used for both the PCM information and the instrument. The yellow and black wires are used for the PCM, and the green wire is used for the instrument. The green wire splits its signal between the dash gauge and the Indicator Control Module. That module uses various sensor inputs to operate dash warning lamps.

There are connectors near the alternator which connect the ignition control module, the alternator L terminal, and the injectors.