What’s up long time lurker first time poster. I have a 2007 cobalt ss supercharged,it sat for about 6 months and when i went to drive it my temp just said”- - -“. I’ve read a few threads on here and seems a lot of people ha e similar issues but i haven’t been able to find what the cause of this is.
My situation. My car doesn’t do what most say and only do this intermittently ever since it started it has never had a temp reading again. I took it to auto zone to have codes read and their scanner wouldn’t even turn on. I took the car home and went through the fuses and found two that were bad and replaced them. Went back the next day and the scanner worked and the only code it pulled was for a coolant temp sensor. I had already replaced the sensor and thermostat prior to this based on threads i read here, decided to replace sensor again this time with a GM part and still nothing. My fans run constantly while the car is on,has problems starting after it’s been sitting and I’ve had it die once while in second gear. Also should there be power running to the coolant temp sensor cause i put a tester on it and the bulb didn’t light up. Any help would be greatly appreciated tyia

 

Sounds like you should check the wiring (and fuses) associated with the coolant temp sensor.

 

i checked all the fuses they’re all good now.
should there be power going to the coolant temp sensor. I’ve read some places they don’t have power going to them and other posts that say it’s a very small amount. If it’s a small amount maybe it’s not enough to light up the bulb? I guess i can follow that down to the next connector and see if i get power there. It’s all under the super charger and i really don’t wanna pull that off.

 

Basically every sensor has power going to it... it wouldn't operate otherwise. So if your sensor has no power, that would be the place to start.

The car runs a 12v system, so the supply should be around that. Most of the output voltages are going to be a 0-5v signal though. If you're checking voltages, make sure your reader/meter is set up for the proper amount of voltage (I.E. don't try to read a 12v system with a 120v tester).

 

i don’t have a meter just one of those testers with the light bulb,i checked on another sensor that i had a good found and it lit up the tester. The sensor i tested it on had 3 nodes and the one to the coolant sensor only has two. Idk i guess I’ll go buy a meter and check it that way. Thanks for the help.

 

Pulled the super charger off today and followed the sensor wires down about 6” at which point i found they had been chewed apart. By the cat food and peanuts piled up behind the super charger my guess is a squirrel sharpened his teeth on my wiring 🙄. I temporarily twisted the wires together,powered on the car and the coolant temp was reading. So i guess if anyone else has this issue check for rodents chewing up your wires before all the other stuff lol

 

A mouse or mice is much more likely. They can certainly do some damage. Hopefully that's the only place they chewed.

 

it could have been a mouse i guess … that’s not really the important part here. I just assumed squirrel because my ole lady feeds them and we have a ton around plus i found longer grey hairs. But yeah after work today I’m gonna see what i can see,if the check engine light comes back on I’ll know what to check into lol.