your on the right plug but you cant test ressistance with the harness still connected and with your leads set up like that you are actually testing resistance to ground rather thatn resistance through the ect.
Heres what you need to do:
1. (With cold engine) Disconect the harness plug and on the lower plug (going down under the intake manifold) put your black lead on one of the pins and the red on another with your meter on the 20k setting. i cant remember which two pin go to the ect bu just try them until you get a reading.
2. Reconnect the plug and warm the engine
3. repeat step one with meter on the 2000 scale