It is most likly a wheel speed sensor, but would need to do a diagnostic to determin if this assumption is correct and if it is, which wheel sensor.
Call us to schedule and appointment:
Christian Brothers Automotive
7937 Westheimer Rd
Houston, TX 77063
713-781-2626
RepairPal Certified shops can diagnose and repair your 2000 Mercury Grand Marquis. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
Thank you for your response. I don't live in the area or I would certainly trust your company to do the needed repairs.