2009 Nissan Xterra Owner's Manual - Page 208

Accelerator downshift - in D position - For passing or hill climbing, depress the accelerator pedal to the floor. This shifts the transmission down into a lower gear, depending on the vehicle speed. OFF: For driving up and down long slopes where engine braking is necessary push the Overdrive switch once. The O/D OFF indicator light in the instrument panel comes on at this time. When cruising at a low speed or climbing a gentle slope, you may feel uncomfortable shift shocks as the transmission shifts into and out of Overdrive repeatedly. In this case, depress the Overdrive switch to turn the Overdrive off. The O/D OFF indicator light in the instrument panel comes on at this time. LSD0142 Overdrive switch Each time your vehicle is started, the transmission is automatically "reset" to overdrive ON. When driving conditions change, depress the Overdrive switch to turn the Overdrive on. Remember not to drive at high speeds for extended periods of time with the Overdrive off. This reduces fuel economy. ON: With the engine running and the shift selector in the D (Drive) position, the transmission upshifts into Overdrive as vehicle speed increases. Overdrive does not engage until the engine has reached operating temperature. 5-16 Starting and driving