where dose the VSS get it power from ?

A vss generates a mV signal, if any sensor has v-ref (reference voltage) its sent by the processor. You can look up your car and its sensor and read various things about it for that model year by googling. diagrams, pics etc would be included, then understanding and testing is all included on one site, that's how I find them, YMM and symptom, or YMM and sensor code stored in memory are two very effective ways to find all the data, and have it pertain to the cause.

A magnet and a winding, then trip it, it generates a signal measured in millivolts. if it's dinged by a foreign object, misshapen, or has a buildup stuck to it, it can malfunction, or it can test out of range. That's all I can say without your year to look up.