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.

Check the back-up battery.
CHECK:

With the ignition switch ON or the engine running, check whether or not this DTC is output again in several hours.

OK:

DTC is not output.
1. OK : Temporary voltage drop, (electric discharge) No problem.
2. NG : Go to next step.
Check for open and short circuit in wire harness and connector between telephone ECU (Mayday ECU) and back-up battery (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
1. NG : Replace or repair wire harness connector.
2. OK : Replace the back-up battery (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
HINT:

If DTC is not cleared even though the battery is replaced, replace the telephone ECU (Mayday ECU).