Implementation of a multifunctional contactless bidirectional charging and discharging system with the aid of giant magnetoresistance (GMR) effect for car parking guidance is proposed. Traditional Hall effect sensors can detect magnetic flux changes. However, if the changes are not significant enough to induce detectable interference voltage, there will be error detection. To remedy, a GMR sensor may detect tiny changes in the magnetic field, which will produce a larger change in resistance; this resistance is less susceptible to external noise influence while generating a relatively stable signal level. As a novel application, our research task combines a GMR sensor, a flexible magnetic stripe constituted by GMRs, a microprocessor and a wireless inductive power/data transfer module to realize a positioning control system for the parking lot's microgrid. Real-world experiments are conducted to verify the proposed approach.