Mute Signal Circuit between Navigation ECU and Stereo Component Amplifier

DESCRIPTION

This circuit sends a mute signal to the stereo component amplifier to enable the voice on the phone to be heard clearly when the cellular phone is used.
If there is an open in the circuit, no sound can be produced from the speakers while the cellular phone is being used.
If there is a short in the circuit, even though the stereo component amplifier is normal, no sound, or only an extremely small sound, can be produced.

WIRING DIAGRAM

INSPECTION PROCEDURE

1. INSPECT STEREO COMPONENT AMPLIFIER

1. Measure the voltage according to the value in the table below.

   Standard voltage:

   Tester connection	Condition	Specified condition
   N-MU - Body ground	Turn ignition switch to ACC, Audio system is playing → Navigation voice is produced	Above 3.5 V → Below 1 V

NG	Go to step 2

OK
RETURN TO THE ORIGINAL INSPECTION FLOW BECAUSE THE CHECK RESULT IS NORMAL

2. CHECK HARNESS AND CONNECTOR (NAVIGATION ECU - STEREO COMPONENT AMPLIFIER)

1. Disconnect the connectors from the navigation ECU and stereo component amplifier.

2. Measure the resistance according to the values in the table below.

   Standard resistance:

   Tester connection	Condition	Specified condition
   MUT2 - N-MU	Always	Below 1 Ω
   MUT2 - Body ground	Always	10 kΩ or higher

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3. INSPECT NAVIGATION ECU

1. Connect the connector to the stereo component amplifier.

2. Measure the voltage according to the value in the table below.

   Standard voltage:

   Tester connection	Condition	Specified condition
   MUT2 - Body ground	Turn ignition switch to ACC	Above 3.5 V

NG	REPLACE STEREO COMPONENT AMPLIFIER (STANDARD SYSTEM)
NG	REPLACE STEREO COMPONENT AMPLIFIER (MARK LEVINSON SYSTEM)

OK
REPLACE NAVIGATION ECU