To my knowledge, You should be able to pull duty cycle readings from the x11 port. Check voltage across pins 2 and 3.

I dont believe there is any prelim setup for a Federal car. Atleast the FSM doesn't indicate anything about doing anything special.

Use this formula to check duty cycle:

Duty Cycle = [1 - (V{pin 3}/V{max})] x 100%

where V{max} is battery voltage.

Once you've done that, if you are seeing a fixed voltage, rather than a relatively dynamic one you should consult this:

http://i98.photobucket.com/albums/l250/MafiaNicky/50006pdf2.png

It should assist you in tracking down the problem.

I used this method on my 93 190E. It should be the same for both of your vehicles.

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