Toyota 4Runner: Microphone Circuit between Microphone and Radio Receiver

Toyota 4Runner Service Manual / Audio / Visual / Telematics / Audio / Video / Audio And Visual System / Microphone Circuit between Microphone and Radio Receiver

DESCRIPTION

The radio and display receiver assembly and map light assembly (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 map light assembly (telephone microphone assembly), and the map light assembly (telephone microphone assembly) sends microphone signals to the radio and display receiver assembly.

WIRING DIAGRAM

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - MAP LIGHT ASSEMBLY (TELEPHONE MICROPHONE ASSEMBLY))

(a) Disconnect the G49 radio and display receiver assembly connector.

(b) Disconnect the U2 map light assembly (telephone microphone assembly) connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
G49-4 (MACC) - U2-14 (MACC)	Always	Below 1 Ω
G49-5 (MIN+) - U2-13 (MCO+)	Always	Below 1 Ω
G49-6 (SNS2) - U2-15 (SNS2)	Always	Below 1 Ω
G49-19 (MIN-) - U2-12 (MCO-)	Always	Below 1 Ω
G49-4 (MACC) - Body ground	Always	10 kΩ or higher
G49-5 (MIN+) - Body ground	Always	10 kΩ or higher
G49-6 (SNS2) - Body ground	Always	10 kΩ or higher
G49-18 (SGND) - Body ground	Always	10 kΩ or higher
G49-19 (MIN-) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

2.	INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY

(a) Reconnect the G49 radio and display receiver assembly connector.

(b) Reconnect the U2 map light assembly (telephone microphone assembly) connector.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
G49-4 (MACC) - Body ground	Ignition switch ACC	4 to 6 V

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G49-18 (SGND) - Body ground	Always	Below 1 Ω
G49-19 (MIN-) - Body ground	Always	Below 1 Ω

Text in Illustration

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

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY

3.	INSPECT MAP LIGHT ASSEMBLY (TELEPHONE MICROPHONE ASSEMBLY)

(a) Disconnect the U2 map light assembly (telephone microphone assembly) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
U2-15 (SNS2) - U2-12 (MCO-)	Always	Below 1 Ω

Text in Illustration

*a	Component without harness connected (Map Light Assembly (Telephone Microphone Assembly))

GO TO STEP 5

4.	INSPECT MAP LIGHT ASSEMBLY (TELEPHONE MICROPHONE ASSEMBLY)

(a) Reconnect the G49 radio and display receiver assembly connector.

(b) Reconnect the U2 map light assembly (telephone microphone assembly) connector.

(d) Connect an oscilloscope to terminals 13 (MCO+) and 12 (MCO-) of the U2 map light assembly (telephone microphone assembly) connector.

Text in Illustration

*a	Component with harness connected (Map Light Assembly (Telephone Microphone Assembly))

(e) Check the waveform of the telephone microphone assembly using the oscilloscope.

Result	Proceed to
A waveform synchronized with the voice input to the map light assembly (telephone microphone assembly) is output	A
A waveform synchronized with the voice input to the map light assembly (telephone microphone assembly) is not output	B

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

5.	REPLACE TELEPHONE MICROPHONE ASSEMBLY

(a) Replace the telephone microphone assembly (See page ).

(b) Check if the same malfunction recurs.

Result	Proceed to
Malfunction does not recur (returns to normal)	A
Malfunction recurs	B

Result

Proceed to

Malfunction does not recur

(returns to normal)

Malfunction recurs

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPLACE MAP LIGHT ASSEMBLY (TELEPHONE MICROPHONE ASSEMBLY)

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