I think it's the yellow line with the green tracer, that, when vacuum is applied to it, will unlock the trunk. You can find this line under the rear seat cushion. (Unless the diaphragm is shot)

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D