Hi all! I have a late 1995 (but considered a 1996) normally aspirated Volvo 850 wagon. I am having trouble with my temp gauge as it always goes to the red mark even with the engine cold and even with ethe ngine not running (just full switch on). I suspected the engine coolant temp (ECT) sensor, so I inplug it and check again. Still the same thing. Temp gauge goes to red mark on ignition to full on. Also, the engine fan runs when I switch the ignition to full on and it continues to run (at least for 5 minutes) even when I switch off. My question is, what is causing the gauge to reach the red mark when the sensor is unplugged? Where is the signal coming from? Is this the default signal that the computer sends to the gauge when there is a bad (or non-existent)temp sensor? I think I have the L H3.2 Fuel Control Unit (which reads the temp sensor analog signal and converts it to a digital signal and sends it to the instrument cluster and the Ignition Control Unit) and the EZ-129K Ignition control Unit. Any thoughts?

Sorry for the long post.

Thanks,
Philip