Mute Signal Circuit between Radio Receiver and Stereo Component Amplifier

DESCRIPTION

This circuit sends a signal to the stereo component amplifier to mute noise. Because of that, the noise produced by changing the sound source ceases.
If there is an open in the circuit, noise can be heard from the speakers when changing the sound source.
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(s) in the table below.

   Standard voltage:

   Tester connection	Condition	Specified condition
   MUTE - Body ground	Turn ignition switch to ACC, Audio system is playing → Changing	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 (RADIO RECEIVER - STEREO COMPONENT AMPLIFIER)

1. Disconnect the connectors from the radio receiver and stereo component amplifier.

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

   Standard resistance:

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

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3. INSPECT STEREO COMPONENT AMPLIFIER

1. Connect the connector to the radio receiver.

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

   Standard voltage:

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

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

NG
REPLACE RADIO RECEIVER