Toyota Lexusc Owner's Handbook Manual page 519

STARTING AND DRIVING
Normal driving mode
" Slip indicator light
Leave the system on during the ordinary driving so that it
can operate when needed.
You may hear a sound in the engine compartment for a few
seconds just after the vehicle begins to move. This means that
the traction control system is in the self-check mode, but does
not indicate a malfunction.
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When the traction control system is operating, the following
conditions occur:
D The system controls the spinning of the front wheels. At this
time, the slip indicator light blinks.
D You may feel vibration or noise in your vehicle, caused by
operation of the brakes. This indicates the system is
functioning properly.
The slip indicator light comes on for a few seconds when the
ignition key is turned to "ON". If the indicator light does not
come on when the ignition is turned on, contact your Lexus
dealer.