temperature gauge not reading/working
 

truck is a 1992 silverado with the 5.7. we changed the thermostat out and im about to change the temperature sensor out aswell. my friend says there is also another sensor, or maybe its a sending unit thats on the drivers side below the valve covers, just above the headers, anyone know what it is? thanks!

edit: the gauge goes all the way to the right when we first start the truck up, then rest back on the left

we replaced the temp sensor on top of the intake, still no glove. even tried switched gauge clusters and it did the same thing when starting up.

we also tried attaching a ground wire to the plug that went into the, what im guessing is the sending unit, and the gauge didnt move, could it be the wiring? any input or ideas would be great

You need to work with the connector with the Dark Green wire.

To test the whole system disconnect that sensor and supply a direct ground supply to that wire, if the gauge pegs full hot then it is the sensor.

To test the sensor using a DVOM check resistance of the sensor to ground when engine is cold. start and warm up the engine and recheck, resistance should go down.

Let us know we are here to help

We attached some copper wire to the plug where I have circled and held it to the frame, while the key was in all positions and even with the truck running, the gauge didn't move. We tried wiggling it around as well, still nothing. I don't currently have an ohm reader with me. Would it be a good idea to cut the plug about 3-4 inches up on the wire, then try hard wiring it to a ground and see what happens(in case the plug is the problem) I'm just weary of trying anything to stupid because it's my daily driver.

http://img7.imageshack.us/img7/20/connector1.jpg
http://img40.imageshack.us/img40/8197/connector2.jpg

edited for pics

If you think that the connector is the problem, I'd just cut back some of the insulation to expose some wire and run a wire from there to a good ground and see if the gauge goes to full hot, if it does, you have a problem in that connector. If you wiggled and tugged the wire at the connector and it didn't break, I doubt that the connector is your problem though. Since you already swapped a known good cluster and bypassed the sensor by grounding the wire and no dice, then you probably have a break in the wire somewhere. Probably easiest to run a new wire from the sensor to the cluster than trying to find the break. You could follow the wire as much as you can see and visually check for a break, and if you can't find anything you'll probably be best off just running a new wire.

So I questioned the friend who said he grounded the wire, and said where he touched the frame was dirty. Took some sand paper to a little spot cleaned it off, gauge read hot. So went back to town and got a "temperature switch" to replace the one that's currently in it. Just waiting now for it to cool down. I'll post results in a little bit.

Cool deal, sounds like you nailed it

That was it! Everything is back to working good. Then we got the truck stuck for a few hours in the mud. Thanks for the help guys!!

Re: temperature gauge not reading/working
 

Your gauge is not effective. I think it is not good at all. I think the sensor is is measuring your physical quantity of temperature and converts it into a signal. You should check out the valve covers.