Pressing the button changes the vehicle-to-vehicle distance as follows:

The vehicle-to-vehicle distance is set automatically to long mode when the engine switch is turned to ignition on mode.
If a vehicle is running ahead of you, the preceding vehicle mark will also be displayed.
Vehicle-to-vehicle distance settings
Select a distance from the table below. Note that the distances shown correspond to a vehicle speed of 50 mph (80 km/h). Vehicle-to-vehicle distance increases/decreases in accordance with vehicle speed.

Adjusting the set speed
Canceling and resuming the speed controlInspection
1. INSPECT THERMOSTAT
HINT:
The valve opening temperature is stamped on the thermostat.
(a) Immerse the thermostat in water and gradually heat the
water.
(b) Check the valve opening temperature.
Valve opening temperature: 80 to 84 C (176 to 183 F)
If the valve opening temperature is ...