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.

Confirm problem symptoms.
CHECK:

Confirm problem symptoms.

RESULT:

A: The guidance voice does not come out.

B: When playing the recorded memos, the voice does not come out.

C: When playing the recorded memos, if finishes in the middle.

D: When playing the recorded memos, the playing time is too long.

E: When playing the recorded memos, the volume cannot be adjusted.
1. B: Go to step 4 .
2. C: Check and replace telephone ECU (Mayday ECU) (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
3. D: Go to step 6 .
4. E: Go to step 6 .
5. A: Go to next step.
Check rear speaker (LH).
CHECK:

Check that the sound is heard from rear speaker (LH) when radio switch is ON.

OK:

Radio sound is heard from rear speaker (LH).
1. NG : Go to "AUDIO SYSTEM" (See PROBLEM SYMPTOMS TABLE ).
2. OK : Go to next step.
Check for open and short of harness and connector between rear speaker (LH) and telephone ECU (Mayday ECU) (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 ).
Check microphone.
CHECK:

Check that the malfunction disappear when known good microphone is installed.

RESULT:

A: Malfunction does not disappear.

B: Malfunction disappear.
1. B: Replace microphone.
2. A: Go to next step.
Check microphone amplifier.
CHECK:

Check that the malfunction disappears when a good microphone amplifier is installed.

RESULT:

A: Malfunction does not disappear.

B: Malfunction disappear.
1. NG : Replace microphone amplifier.
2. OK : Go to next step.

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

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 (Overhead 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 ).