Lights for service and ABS remain dark when ignited

Hello dear Volvo community, the symptom is already in the subject. Can the two control lamps be simply and touchingly defective? There is a defective front right wheel sensor in the fault memory. But then the ABS light should at least be on. However, it remains dark during the start process. It is a 850 T5 Bj.9/95, so probably MJ. 96. Has any of you experience with this situation. Thanks for all helpful hints. Greetings, Ulf