Temp sensor

How would i know if the temp sensor is bad? reason is that the guage on the dash never moves even when the engine is hot. i have a picture of how someone half-as*ed the connection to the sensor too, im sure this may have something to do with why the guage isnt working as well. it still has a solid contact to the sensor with a round plastic connecter, but im thinking of just putting a new sensor and connecter on the wires, i just want to be sure that this is my problem though. anyway have a look: http://i15.photobucket.com/albums/a367/pctvman/c002-1.jpg

That sensor (with the yellow and black wires) is the temperature sensor which reports to the ECM, not the dash instrument. The sensor for the dash gauge should have a single green wire attached to it, and should be located in the LH cylinder head between and below the #1 and #3 spark plugs.

ohhhhh wow so i was wrong, maybe that sensor is still good. ill have a look at the other one you mentioned then. how can you visualy tell if something like that is bad or not???

ohhhhh wow so i was wrong, maybe that sensor is still good. ill have a look at the other one you mentioned then. how can you visualy tell if something like that is bad or not???

You can't, aside from ensuring that green wire is in physical contact with the terminal on the sending unit.

You can ohm it out across a range of temperatures and compare that to the ohms required for any given temperature to determine if the sending unit is bad. Or, you can spend the $5 or so on a new sender.

yeah i think ill just end up doing that, maybe replace both sensors too. that should get the guage working again then?

one other thing, does the sensor that reports to the ECM need to be good in order for the guage sensor to work or are they 2 seprate things?

They are two separate things. One is a sensor and one is a sender. The difference is that the sensor reports to the ECM to ensure optimal air/fuel mixture, and the other one (sender) displays temperature on a gauge. They are independant of each other.

You can verify that the dash gauge is working by grounding the green wire for the sender. The gauge should move to full-scale hot if it is working properly.

FWIW, most GM temperature sensors have a resistance curve similar to the chart:

http://72.19.213.157/files/CTSMAT.gif