Ford Grand Marquis Owner's Manual page 167

R (Reverse)
With the gearshift in the R (Reverse) position,
the vehicle will move backward. You should
always come to a complete stop before shifting
into or out of R (Reverse).
N (Neutral)
As in P (Park), there is no power transferred
through the transmission. However, the final
drive is not locked so the wheels are free to
rotate. The vehicle may be started in the N
position, but the ignition key cannot be
removed.
Driving
Your vehicle's gearshift is on the steering
column. The Transmission Control Switch (TCS)
is located on the end of the gearshift lever. The
Transmission Control Indicator Light (O/D OFF)
is located on the instrument panel. You can put
the gearshift lever in any of the several
positions.
The O/D OFF light is off (not illuminated)
during normal vehicle operation. This allows the
transmission to upshift and downshift from 1st
through 4th gears. When the TCS is pressed, the
Transmission Control Indicator Light will
illuminate (O/D OFF) on the instrument panel.
When this O/D OFF is illuminated the
transmission will upshift and downshift from 1st
through 3rd gears.
If the O/D OFF light does not come "on" when
the TCS is depressed or if the light "FLASHES"
when you are driving, have your vehicle
serviced at the first opportunity. If this condition
persists, damage could occur to the transmission.
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