Measurement with and without adapter
WARNING: This page is about a different car, the 2013 BMW X5, 2012 BMW X5, and 2011 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.
In the case of measurement without adapter, the second Control module (SG2) is disconnected. Upper circuit. For this measurement, the signal level is only measured via the resistance R. This is why a measurement without adapter leads to a double signal level.
In the case of measurement with adapter, the second Control module (SG2) remains connected. The signal level is then measured via the parallel circuit of resistances R and R2. Lower circuit.