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 controlOn-vehicle inspection
1. DOOR LOCK FAIL-SAFE
(a) When a malfunction in the door control switch (manual switch, operation
interlocked with key) has been
detected, door LOCK/UNLOCK operation become disabled.
2. CHECK ELECTRICAL DOOR LOCK OPERATION
(a) Check the basic function.
Check that all doors lock when ...