Hello im new here and have a car i got for my son it runs great but the coolant fan stays on after i turn key off even when cold.swapped out all temp sensors and switches .if i unplug the ect under the distributor the fan shuts off. So unplugged sensor to shut it off.mybsmall scanner says its reading -40 also at the plug with the sensor unplugged im getting 12v is that normal?swapped out the fan module behind glovebox with ones i grabbed from salvage yard i have 3 but still problem persists.i would wire a relay off one of the temp switches to kick fan off and on but the cel light will stay on and im adsumingbthe fuel values will be affected but the misreading sensor.please im hoping somones dealt with this before .i am stumped im assuming there should be 5 volts going to that sensor and thats why its reading like its - 40..and the code im getting is p0118 temp sensor 1 circuit high.also tgis car has a hard time starting when its cold.i jusy opened the ecu and found 3 large solder joints cracked so i soldered those ..so hopefully.tia tomorrow morning when its cold outside ill be able to see if i fixed that issue.pleasr forgive my crappy typing im using my phone and i dont have my readers on.TIA!

 

Cooling fans running for a few minutes after the engine is shut off is normal. Odd that it would do it while cold, though.

 

Yes i can go outside first thing in am start it up and turn it right off and fan comes on..but with engine running it wont come on.this thing is kicking my butt.

 

well it did the hard start thing..still code p0118 but dont think thats causing harf start on cold days.gonna check for spark and fuel.once it starts it runs great and starts right up.thinking might be bad ecu causing all the issues

 

Don't know if still unresolved but here is a possible cause.
Last year I was working on a 08 Toyota Yaris. had to remove air box and other things to access other parts . Well... when I put it back together and sttarted the car. It had the radiator fan going even though the key was removed.! Only way to stop the fan was to disconnect the battery. Once reconnected everything was seemingly normal until I start the engine again.
It took me a few minutes to realize I forgot to fasten one of the main ground attachments. A missing main ground ( battery to frame or engine to frame) will cause erratic behaviors like that.
Just thought I should share this little discovery.
Good luck