2001 peterbilt 379 Detroit 12.7 60 series fan won't stop running.

First time poster on this site and want to just say thank you in advance for the help. I have a 2001 peterbilt 379 with a 12.7 detroit series 60 and the engine fan will not stop running. I checked the solenoid it has 12 volts I changed the 2 prong sensor that goes from head to ecm. Checked all fuses except for the ones behind the switch panel in the dash because I can't find anywhere that says what they are. I have good air going to the solenoid and air out. Also this all started when my engine temp gauge started to not work. It stays under 100 until I shut the truck down and then it goes up to almost 180. Any ideas for what is wrong would be great.

 

So there is 3 on that side of the head. Far right is the ECM with power and ground the other 2 is what I'm not sure which one is which.....I also put a volt meter on those and there only getting around 4 volts. Should they all be getting 12?

 

Awesome thank you. Also with the key one and the manual fan switch in the on position in the dash I do not have power to the solenoid....is that how they work no power to the solenoid to engage it?

 

Yes so with the key on but not running and switch off I have 12 volts going to the solenoid and if plug it and unplug it the solenoid releases air. But when the truck is running and the switch on or off it doesn't make a difference I did the same thing and plugged and unplugged and nothing happens. I'm not sure that all made sense and kind of confusing to read.

 

Yes so that is the sensor that I have already changed. The other sensors are single post. I know one goes to the gauge but I don't know what the other single post sensor does.