Toyota 4Runner: Telephone Microphone Error (B1572)

Toyota 4Runner Service Manual / Audio / Visual / Telematics / Cellular Communication / Safety Connect System / Telephone Microphone Error (B1572)

DESCRIPTION

This DTC is stored when the DCM (Telematics Transceiver) detects a malfunction in the telephone microphone assembly circuit.

DTC Code	DTC Detection Condition	Trouble Area
B1572	Current of MCVD reaches the malfunction criteria for 10 seconds when the ignition switch is ON.	Harness or connector Telephone microphone assembly Map light assembly DCM (Telematics Transceiver)

WIRING DIAGRAM

PROCEDURE

1.	CHECK FOR DTC

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(d) Perform "Health Check" and check for current DTCs (See page ).

Result

Result	Proceed to
DTC B1572 is output	A
DTC B1572 is not output	B

CHECK FOR INTERMITTENT PROBLEMS

2.	CHECK MAP LIGHT ASSEMBLY (TELEPHONE MICROPHONE POWER SOURCE)

(a) Remove the map light assembly with the connector connected (See page ).

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
U2-14 (MACC) - Body ground	Ignition switch ON	4 to 6 V

Text in Illustration

*a	Component with harness connected (Map Light Assembly)

GO TO STEP 5

3.	CHECK HARNESS AND CONNECTOR (DCM - MAP LIGHT ASSEMBLY)

(a) Disconnect the F39 DCM (Telematics Transceiver) connector.

(b) Disconnect the U2 map light assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
F39-34 (MCI+) - U2-13 (MCO+)	Always	Below 1 Ω
F39-35 (MCI-) - U2-12 (MCO-)	Always	Below 1 Ω
F39-34 (MCI+) - Body ground	Always	10 kΩ or higher
F39-35 (MCI-) - Body ground	Always	10 kΩ or higher
F39-32 (SGND) - Body ground	Always	10 kΩ or higher

Text in Illustration

Front view of wire harness connector

(to DCM [Telematics Transceiver])

Front view of wire harness connector

(to Map Light Assembly)

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	REPLACE TELEPHONE MICROPHONE ASSEMBLY

(a) Replace the telephone microphone assembly with a normal one and check that the same problem does not occur again (See page
).

OK:

The system returns to normal.

END

REPLACE MAP LIGHT ASSEMBLY

5.	CHECK DCM (TELEMATICS TRANSCEIVER) (TELEPHONE MICROPHONE POWER SOURCE)

(a) Remove the DCM (Telematics Transceiver) with the connectors connected (See page ).

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
F39-33 (MCVD) - Body ground	Ignition switch ON	4 to 6 V

Text in Illustration

*a	Component with harness connected (DCM [Telematics Transceiver])

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.	REPLACE DCM (TELEMATICS TRANSCEIVER)

(a) Replace the DCM (Telematics Transceiver) (See page ).

NOTICE:

The ignition switch must be off.
Do not replace the DCM (Telematics Transceiver) with one from another vehicle.

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