Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Microphone Circuit

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Audio & Visual & Telematics / Audio / Video / Audio And Visual System (for 12.3 Inch Display) / Microphone Circuit

DESCRIPTION

  • The radio receiver assembly and telephone microphone assembly are connected to each other using the microphone connection detection signal lines.
  • Using this circuit, the radio receiver assembly sends power to the telephone microphone assembly, and the telephone microphone assembly sends microphone signals to the radio receiver assembly and navigation ECU.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Depending on the parts that are replaced during vehicle inspection or maintenance, performing initialization, registration or calibration may be needed. Refer to Precaution for Audio and Visual System.

Click here

PROCEDURE

1.

CHECK MICROPHONE AND VOICE RECOGNITION (INPUT TO NAVIGATION ECU)

(a) Enter the "Microphone Check" screen. Refer to Check Microphone (Input to navigation ECU) in Operation Check.

Click here

(b) When voice is input into the microphone, check that the microphone input level meter changes according to the input voice.

OK:

Check result is normal.

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

CHECK MICROPHONE AND VOICE RECOGNITION (INPUT TO RADIO RECEIVER ASSEMBLY)

(a) Enter the "Microphone Check" screen. Refer to Check Microphone (Input to radio receiver assembly) in Operation Check.

Click here

(b) When voice is input into the microphone, check that the microphone input level meter changes according to the input voice.

OK:

Check result is normal.

NG

GO TO STEP 5

OK

3.

CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - NAVIGATION ECU)

(a) Disconnect the J149 radio receiver assembly connector.

(b) Disconnect the J153 navigation ECU connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

J149-25 (MCO+) - J153-13 (MIC+)

Always

Below 1 Ω

J149-26 (MCO-) - J153-14 (MIC-)

Always

Below 1 Ω

J149-25 (MCO+) or J153-13 (MIC+) - Body ground

Always

10 kΩ or higher

J149-26 (MCO-) or J153-14 (MIC-) - Body ground

Always

10 kΩ or higher

J149-24 (SGND) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

INSPECT RADIO RECEIVER ASSEMBLY (OUTPUT TO NAVIGATION ECU)

(a) Disconnect the J153 navigation ECU connector.

(b) Turn the engine switch on (ACC).

(c) Check the signal waveform according to the condition(s) in the table below.

Item

Condition

Measurement terminal

J153-13 (MIC+) - J153-14 (MIC-)

Tool setting

50 mV/DIV., 500 ms/DIV.

Vehicle condition
  1. Turn the engine switch on (ACC).
  2. Sound is input to the telephone microphone assembly when the user is closer than 125 mm from the telephone microphone assembly sound holes in the roof headlining holder cover.

OK:

The waveform is similar to that shown in the illustration.

HINT:

The oscilloscope waveform shown in the illustration is an example for reference only.

*a

Front view of wire harness connector

(to Navigation ECU)
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPLACE RADIO RECEIVER ASSEMBLY

5.

CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - TELEPHONE MICROPHONE ASSEMBLY)

(a) Disconnect the J151 radio receiver assembly connector.

(b) Disconnect the U15 telephone microphone assembly connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

J151-25 (SNS2) - U15-3 (SNS2)

Always

Below 1 Ω

J151-23 (MACC) - U15-1 (MACC)

Always

Below 1 Ω

J151-21 (MIN+) - U15-2 (MCO+)

Always

Below 1 Ω

J151-22 (MIN-) - U15-4 (MCO-)

Always

Below 1 Ω

J151-25 (SNS2) or U15-3 (SNS2) - Body ground

Always

10 kΩ or higher

J151-23 (MACC) or U15-1 (MACC) - Body ground

Always

10 kΩ or higher

J151-21 (MIN+) or U15-2 (MCO+) - Body ground

Always

10 kΩ or higher

J151-22 (MIN-) or U15-4 (MCO-) - Body ground

Always

10 kΩ or higher

J151-24 (SGND) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

6.

CHECK RADIO RECEIVER ASSEMBLY

(a) Remove the radio receiver assembly with the connector(s) still connected.

*a

Component with harness connected

(Radio Receiver Assembly)

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

J151-23 (MACC) - Body ground

Engine switch on (ACC)

4 to 6 V

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

J151-22 (MIN-) - Body ground

Always

Below 1 Ω

J151-24 (SGND) - Body ground

Always

Below 1 Ω
NG

REPLACE RADIO RECEIVER ASSEMBLY

OK

7.

CHECK TELEPHONE MICROPHONE ASSEMBLY (OUTPUT TO RADIO RECEIVER ASSEMBLY)

*a

Component with harness connected

(Telephone Microphone Assembly)

(a) Check the output waveform.

(1) Remove the telephone microphone assembly with the connector(s) still connected.

(2) Connect an oscilloscope to terminal U15-2 (MCO+) and U15-4 (MCO-).

(3) Turn the engine switch on (ACC).

(4) Sound is input to the telephone microphone assembly when the user is closer than 125 mm from the telephone microphone assembly sound holes in the roof headlining holder cover.

(5) Check the signal waveform according to the condition(s) in the table below.

Item

Condition

Measurement terminal

U15-2 (MCO+) - U15-4 (MCO-)

Tool setting

50 mV/DIV., 500 ms/DIV.

Vehicle condition
  1. Engine switch on (ACC)
  2. Sound is input to the telephone microphone assembly when the user is closer than 125 mm from the telephone microphone assembly sound holes in the roof headlining holder cover.

OK:

The waveform is similar to that shown in the illustration.

HINT:

The oscilloscope waveform shown in the illustration is an example for reference only.

OK

REPLACE RADIO RECEIVER ASSEMBLY

NG

REPLACE TELEPHONE MICROPHONE ASSEMBLY

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