I'm sure James can shed more light than myself, but I fully expect that the combination of resistors basically sets up the unit, for a particular gear ratio or some such.

The ignition system on the early 124 gassers works a similar way. There is a resistor that plugs into a socket near the master cylinder. The resistance provides a setting for a particular maximum ignition advance. Remove it and you get max ignition advance but premium fuel is required. Different resistances retard ignition to different levels for use of different fuel grades.

Some ROW cars have a dial in the resistors place so that you can set for different octane ratings. This is a more necessary feature in some countries were high grade fuel is difficult or impossible to obtain.

Sorry for the diversion from the thread subject.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

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