Why doesnt the overdrive kick in on your 1995 Mercury Tracer with automatic transmission?

The overdrive in a 1995 Mercury Tracer may not engage due to several potential issues, such as a faulty overdrive switch, a malfunctioning transmission control module, or low Transmission Fluid levels. Additionally, issues with the throttle position sensor or a slipping transmission can prevent overdrive from activating. It's advisable to have the vehicle diagnosed by a professional to identify the specific cause and necessary repairs.