Toyota Tacoma (2015-2018) Service Manual: Microphone Circuit between Microphone and Radio Receiver

Toyota Tacoma (2015-2018) Service Manual / Audio / Video / Audio And Visual System / Microphone Circuit between Microphone and Radio Receiver

DESCRIPTION

The radio and display receiver assembly and telephone microphone assembly are connected to each other using the microphone connection detection signal lines.

Using this circuit, the radio and display receiver assembly sends power to the telephone microphone assembly, and the telephone microphone assembly sends microphone signals to the radio and display receiver assembly.

WIRING DIAGRAM

PROCEDURE

1.	CHECK MICROPHONE

(a) Enter the "Microphone Check" screen.

Refer to Check Microphone in Operation Check.

Click here

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

OK:

Check result is normal.

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

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

(a) Disconnect the R31 radio and display receiver assembly connector.

(b) Disconnect the T26 telephone microphone assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
R31-4 (MACC) - T26-1 (MACC)	Always	Below 1 Ω
R31-5 (MIN+) - T26-2 (MIC+)	Always	Below 1 Ω
R31-19 (MIN-) - T26-4 (MIC-)	Always	Below 1 Ω
R31-6 (SNS2) - T26-3 (SNS2)	Always	Below 1 Ω
R31-4 (MACC) - Body ground	Always	10 kΩ or higher
R31-5 (MIN+) - Body ground	Always	10 kΩ or higher
R31-19 (MIN-) - Body ground	Always	10 kΩ or higher
R31-18 (SGND) - Body ground	Always	10 kΩ or higher
R31-6 (SNS2) - Body ground	Always	10 kΩ or higher

(d) Reconnect the radio and display receiver assembly connector.

(e) Reconnect the telephone microphone assembly connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY

(a) Remove the radio and display receiver assembly with connectors still connected.

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
R31-4 (MACC) - Body ground	Ignition switch ACC	4 to 6 V

*a	Component with harness connected (Radio and Display Receiver Assembly)

Standard Resistance:

Tester Connection	Condition	Specified Condition
R31-19 (MIN-) - Body ground	Always	Below 1 Ω
R31-18 (SGND) - Body ground	Always	Below 1 Ω

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

4.	INSPECT TELEPHONE MICROPHONE ASSEMBLY

(a) Remove the telephone microphone assembly.

Click here

*a	Component without harness connected (Telephone Microphone Assembly)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
3 (SNS2) - 4 (MIC-)	Always	Below 1 Ω

Click here

REPLACE TELEPHONE MICROPHONE ASSEMBLY

5.	INSPECT TELEPHONE MICROPHONE ASSEMBLY

(a) Turn the ignition switch to ACC.

*a	Component with harness connected (Telephone Microphone Assembly)

(b) Connect an oscilloscope to terminals 2 (MIC+) and 4 (MIC-) of the telephone microphone assembly connector.

Result

Result	Proceed to
A waveform synchronized with the voice input to the amplifier microphone assembly is output	A
A waveform synchronized with the voice input to the amplifier microphone assembly is not output	B

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPLACE TELEPHONE MICROPHONE ASSEMBLY

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