Inspection Procedure
WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.
Replace the telephone ECU (Mayday ECU) (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
HINT:
If DTC is not cleared even through the Mayday ECU is replaced, replace the Mayday Assembly (Transceiver, Back-up battery, Bus buffer ECU and Mayday ECU).