Lexus GS430 User Manual page 460

STARTING AND DRIVING
Install all 4 tires of specified size at appropriate
pressure: The anti−lock brake system detects vehicle
speeds using the speed sensors for respective wheels'
turning speeds. The use of tires other than specified
may fail to detect the accurate turning speed resulting
in a longer stopping distance.
436
"ABS" warning light
G31080
" 1 U.S.A.
2 Canada
GS430—The light comes on when the engine switch is
selected in "IG−ON" mode. If the anti−lock brake system and
the brake assist system work properly, the light turns off in a
few seconds after the engine is started.
GS300—The light comes on for a few seconds when the
engine switch is selected in "IG−ON" mode. It indicates the
anti−lock brake system and the brake assist system work
properly.
If either system malfunctions, the light comes on again.
When the "ABS" warning light is on, the anti−lock brake system
and the brake assist system do not operate, but the brake
system still operates conventionally.