In Reply to: Mass Air Flow sensor testing posted by Jean on April 06, 2001 at 10:08:38:
The sensor has two functions. First is air temperature measurement. This can be read with an Ohm meter between terminals 1 and 3 ( might be 1 and 2) 68F= 2.2-2.7k ohms, 122F=.76-.91k. The next is air flow in normal liters per minute. This can also be checked with an Ohn meter between terminals 1 and 2 ( might be 1 and 3 ). As the flapper is pushed open the resistance goes down. But the output must be smooth and free of dropout. I think the resistance here should be about 2.0k ohms. If you get smooth output from the Air Flow Flapper, and respectable resistance from the temp sensor, the unit is good. The major cause of failure is erratic resistance at the closed position, so tap on the flapper to make sure it's rock solid.
You can E Mail me if you are in doubt.