Lexus 2004 GX470 Owner's Manual page 227

STEERING WHEEL AND MIRRORS
CAUTION
Do not adjust the display while the vehicle is moving.
Be sure to adjust the display only when the vehicle is
stopped.
Calibrating the compass (circling calibration)
To rectify the compass, stop the vehicle and push and hold the
"COMP" switch until "C" appears on the display.
There is also a case that "C" appears on the display in case of
the drastic change of the magnetic field.
212
Drive the vehicle slowly (at 8 km/h [5 mph] or lower) in a circle
until the direction is displayed. If there is not enough space to
drive in a circle, drive around the block until the direction is
displayed.
After driving in 1 to 3 circles in the above method, calibration
is complete with the direction shown on the display.