When To Use Overdrive (D With Overdrive Activated); Cancelling Overdrive - Ford Probe Owner's Manual

Once the gearshift is secure in the desired
position, release the brake pedal and use the
accelerator as necessary.
Driving
When to use Overdrive (D with Overdrive
activated)
Overdrive is the usual driving position for an
automatic overdrive transaxle. It works the same
way Drive (Overdrive OFF) works, automatically
upshifting or downshifting as the vehicle speeds
or slows.
However, Overdrive also shifts into a fourth
gear —an overdrive gear — when your vehicle
cruises at a consistent speed for any length of
time. This fourth gear will increase your fuel
economy when you travel at cruising speeds.

Cancelling Overdrive

Overdrive may not be appropriate for certain
terrain. If the transaxle shifts back and forth
between third and fourth gears while you are
driving on hilly roads, select Drive (Overdrive
OFF) by cancelling Overdrive as outlined below.
The Overdrive Off (O/D OFF) button is located
on the gearshift. The Overdrive Off (O/D OFF)
light is located in the instrument cluster.
The O/D OFF light is not illuminated during
normal vehicle operation. This allows the
transaxle to upshift and downshift from 1st
through 4th gears. When the O/D OFF button is
pressed, Overdrive is cancelled and the O/D
OFF light in the instrument cluster illuminates.
When the O/D OFF light is illuminated, the
transaxle will upshift and downshift from 1st
through 3rd gears.
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