Lexus 2003 SC430 Owner's Manual page 113

COMFORT ADJUSTMENT
Adjusting seat cushion angle and height
16sa04b
Move the control switch in the desired direction.
Releasing the switch will stop the seat cushion in that position.
96
Adjusting lumbar support
16sa05b
Push the control switch on either side.
The amount of lumbar support will change while the switch is
pushed.