service interval LEXUS LS430 2003 Factory Repair Manual

If the communication is normal when the tool is connected to another vehicle, inspect the DLC3 on
the original vehicle.
If the communication is still impossible when the tool is connected to another vehicle, the problem
is probably in the tool itself, so consult the Service Department listed in the tool's instruction
manual.
1.INDICATOR CHECK
a. Turn the ignition switch to the ON position while pressing the A/C control AUTO switch and R/F
(Recirculation/Fresh) switch simultaneously.
Fig. 13: Identifying Auto Switch (W/O LEXUS Navigation System)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
b. Check that the all indicators come on and go off 4 times in succession at 1 second intervals.
HINT:
After the indicator check is completed, the system enters the DTC mode automatically.
Press the "OFF" switch to cancel the indicator mode.