I am having issues with my coolant temperate sensor. The problem I am having is that I am using TunerPro RT and it is displaying the temperature at -39.99 or 38.XX degrees, depending on if I have the current one plugged in or my new one that isn't in the manifold, or if I have it jumped. I checked the voltage at the sensor, sensor unplugged, 4.9/5 volts. So then I checked the yellow wire (C10 I think it is) on the ECM and it read 5 volts. So then I plugged in the sensor, 2.2 volts on the open air sensor, 3.3 on the intake manifold.... now I am at a total loss.

Any body have any other ideas for my to try out? This has happened on three different ECMs now and I think it is the reason my car is running really rich and idles high.

 

The yellow wire is C16 and the ground is C10,ECM applies the 5 volts on the C16 wire (yellow)when the sensors get warm the resistance becomes less.At normal engine temps the voltage will be about 1.5 to 2.0 at the C16 terminal.
I usually check these two guys the next day(overnight cooling)As long as they are within two degrees of each other I am satified.There is a temps-resistance chart for these sensors.41 degrees would be about 7280 ohms...I would say your signal voltage is good,and cannot say if the 2.2 or 3.3 would be good or bad.It depends how you read them if the engine was warm it would read different then the one sitting outside?..Thats why I say let them cool overnight and first thing in the morning check them again should be close if not Your on the right track...

 

Hey, thanks for the advice. Since it has sat overnight now I'll see how close they are. However, one thing I did discover is that I think the CTS is okay, I loaded up good old Moates GM ECM DOS program and the coolant temp was just fine, loaded up Tuner Pro R/T and noticed that the Startup temp was correct, however the "live" temp was not. I think there is an error in the ADS file for the $32B.

 

Justed purchased an old OTC scanner and in the info its states that anytime you check a temp sensor..a display of -40F or -40C indicates an open in the coolant circuit.A display of 185C or 366F may indicate a short in that circuit.Just thought I throw that at ya in case you still have a prob...