Each alternator emits a D+ signal at engine start-up. In modern vehicles with an intelligent alternator, however, it is difficult to tap it. But various accessories onboard require this signal. The Dometic Büttner D+ active simulator helps you quickly. And at a fair price. The tiny device (only 17 x 36 mm in size) is simply fastened in the engine compartment with cable ties. When the engine starts, the smart simulator is automatically activated by the vibrations – and switches off automatically when the engine is stopped. The integrated LED light indicates the operating status.