Am I doing this right?
Testing and setting the Duty Cycle on a California spec 1988 300TE with Craftsman meter set to %.
Setup...
Key in, Ignition on, diagnostic set to solid LED by holding for 2 seconds and then again.....

Red into red on the meter and black into black or sensor plug on the meter...
Ok, on the car, first I plug the Red lead into socket pin 3 and the black into 2...


Reads 14.8%....????


Reverse the wires... black to 3 and red to 2... reads 85.1% as it should for Cal spec car.




Retest with red removed from 2....... no change?????




Here is the reading using Black to 3 and red to 2... engine warmed up and running nice..... fluctuates about 50% +- 5ish.



Now, is this the right way to do it?
Is that reading about right?

I have not closed the charcoal canister connection because I dont know which one it is!

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2009 Mercedes ML320 Bluetec