I have these wires in my center console of a retired FedEx truck but w/o any switches. As I understand it the S126 is most likely for a door lock switch. The S48 ASR. Does anyone know what the S90 is for?
Try the T1N manual collection at http://aie-services-2.net/Sprinter/ for an electrical diagram. Use that information with discretion, as the electrical diagrams are not consistent among years or within models.