2003 Mercury Grand Marquis - Transmission issue

trans. wont kick down when hitting passing gear

On older auto-equipped vehicles (like my truck) that’s done with a mechanical linkage, throttle position on the carb to the transmission. With yours, most likely it’s done electronically, based on the throttle position and vehicle speed. So good chance the problem is a fault in some combo of

  • Throttle position sensor
  • Vehicle speed sensor
  • Transmission (possibly solenoid)