If the first sentence is correct (... in steps of 0.1 [tooth]), this should perhaps read 'the range is 30 teeth with a resolution of 0.1 tooth' or 'The range is 30 teeth with a resolution of 0.1 tooth', since step size and resolution are essentially synonymous in a digital system.

Alternatively, the resolution at the level (indirectly) referred to here may be only one tooth, in which case the text should read 'the resolution is 1 tooth over 30 teeth'.

I suggest asking the client for clarification. The English is not exactly native UK/US quality.

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Note added at 46 mins (2008-12-12 12:12:04 GMT)
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Sorry, I meant to say 'Over a range of 30 teeth with a resolution of 0.1 tooth' as the second wording in the first interpretation.

The tooth count is programmed in steps of 0.1 up to 30 Teeth. This allows you to provide a correct speed indication in case of use of the terminal ‘W’ of the Charging Alternator. Above 30 teeth, the resolution jumps to 1 tooth increments. The overspeed is then automatically increased 10%, during the Engine Bypass Time.

I have reworded it for you to read correctly. When you use numerical letters in the beginning you should contionue to use them in the whole text.