AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM (for Knobless Radio and Display Receiver): Microphone Circuit; 2023 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [09/2022

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM10000000271X6
Model Year Start: 2023	Model: GR Corolla	Prod Date Range: [09/2022 - ]
Title: AUDIO / VIDEO: AUDIO AND VISUAL SYSTEM (for Knobless Radio and Display Receiver): Microphone Circuit; 2023 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [09/2022 - ]

Microphone Circuit

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.

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PROCEDURE

1.	CHECK MICROPHONE

(a) Enter diagnostic mode.

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*a	Mic 1 Input Level

(b) Select "Function Check/Setting" from the "Service Menu" screen.

(d) Speak into each microphone assembly and check the microphone input level gauge display.

OK:

The microphone input levels of the gauge change in accordance with the voice.

Result	Proceed to
Microphone input levels change for microphone 1	A
Microphone input level does not change for microphone 1	B

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

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

(a) Disconnect the I185 radio and display receiver assembly connector.

(b) Disconnect the T24 telephone microphone assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
I185-5 (MIN+) - T24-2 (MO1+)	Always	Below 1 Ω
I185-19 (MIN-) - T24-4 (MO1-)	Always	Below 1 Ω
I185-4 (MACC) - T24-1 (MAC1)	Always	Below 1 Ω
I185-6 (SNS) - T24-5 (SNS1)	Always	Below 1 Ω
I185-5 (MIN+) or T24-2 (MO1+) - Body ground	Always	10 kΩ or higher
I185-19 (MIN-) or T24-4 (MO1-) - Body ground	Always	10 kΩ or higher
I185-4 (MACC) or T24-1 (MAC1) - Body ground	Always	10 kΩ or higher
I185-6 (SNS) or T24-5 (SNS1) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY (MACC, MIN-)

(a) With the I185 radio and display receiver assembly connector connected, disconnect the T24 telephone microphone assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
T24-4 (MO1-) - Body ground	Always	Below 1 Ω

Standard Voltage:

Tester Connection	Condition	Specified Condition
T24-1 (MAC1) - Body ground	IG ON	7.5 to 8.5 V

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

4.	INSPECT TELEPHONE MICROPHONE ASSEMBLY (OUTPUT TO RADIO AND DISPLAY RECEIVER ASSEMBLY)

(a) Using an oscilloscope, measure the waveform according to the condition(s) in the table below.

Item	Condition
Tester Connection	T24-2 (MO1+) - T24-4 (MO1-)
Tool setting	50 mV/DIV., 500 ms/DIV.
Vehicle condition	Turn the ignition switch to ON Sound is input to the telephone microphone assembly when the user is closer than 125 mm from the microphone case sound holes.

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.
In order to ensure that a consistent sound level is input to the microphone, use a digital voice recorder, etc., to play back sound in the same location with respect to the microphone.

*a	Component with harness connected (Telephone microphone assembly)

Result	Proceed to
A waveform synchronized with voice signals is output	A
A waveform synchronized with voice signals is not output	B

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

REPLACE TELEPHONE MICROPHONE ASSEMBLY