My ECT sensor ( the gizmo under the thermostat) is possibly not working on my 95- 850. The codes read that it is faulty. It is relatively new. In order to get an exchange, I need to PROVE it's bad. I don't want to be embarrassed, so I picked up a multi-meter.
OK...I got a Multimeter. I am electronically ignorant...a moron! The Ohms section has 5 choices: 2000K, 200k, 20k,2000, 200. What do I set it on for testing the ECT sensor? What am looking for? A simple explanation would be helpful...make believe you are talking to a 5 year old...an not a bright one!!!

Here is a good tutorial on the use of a multimeter to measure resistance.

http://www.ladyada.net/library/metertut/resistance.html

What you want is resistance reading, so 20,000 Ohms will work. Each notch down will just give you better accuracy, so if you are set at 2,000 then it will be easy to read.
The resistance is relative to temperature, the colder the engine the higher the resistance:
32F = 7200
68F = 2800
104F = 1200
212F = 150

Klaus
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The more I learn, the more I forget. So why learn?

OK...so here's what I did:
Engine cold...85 degrees out all day. The meter set at 2000, the reading was 1740, at 20K 1.75....I let it heat up to operating temp (via the interior gauge): at 2000= 225, at 20K .25 This kinda corresponds to your chart, but not exactly. It did go down!
So, if it's not the sensor, then I guess it's the leads going to the sensor...those barrel connections that I can't get inside of to clean. I used a very small jewlers file to try to rough up the inside of the barrel, but the Code still comes up.
Any ideas?

Your sensor seems to be within range, I doubt that the engine is at 212F unless you really let it cook.

Check the female end of the plug, sometimes the contacts get push into the plug. You could push on the wires to get the prongs to move forward a little.

Klaus
--
The more I learn, the more I forget. So why learn?