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 Mayday switch (Overhead J/B).

PREPARATION:

Disconnect the Mayday switch connector.

CHECK:

Check that the continuity exists between terminals of Mayday switch when each switch is pressed.

OK:

TESTER CONNECTION SPECIFICATION

Switch position	Tester connection	Specified condition
Service Play back Record	1 - 2	Continuity
Emergency Volume UP Volume DOWN	2 - 3	Continuity

Fig 1: Checking Mayday Switch (Overhead J/B)

NG : Replace the Mayday switch [overhead J/B).
OK : Go to next step.

Check for open and short circuit in harness and connector between telephone ECU (Mayday ECU) and Mayday switch (over head J/B) (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
1. NG : Repair or replace harness or connector.
2. OK : Check and replace telephone ECU (Mayday ECU) (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).