Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM100000001DTPW
Model Year Start: 2019 Model: Sienna Prod Date Range: [08/2018 -           ]
Title: CELLULAR COMMUNICATION: SAFETY CONNECT SYSTEM: B1572; Telephone Microphone Error; 2019 - 2020 MY Sienna [08/2018 -        ]

DTC

B1572

Telephone Microphone Error

DESCRIPTION

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

DTC No.

DTC Detection Condition

Trouble Area

B1572

Current of MCVD reaches malfunction criteria for 10 seconds while ignition switch is ON.
  • Wire harness or connector
  • Microphone amplifier assembly
  • DCM (Telematics Transceiver)

WIRING DIAGRAM

PROCEDURE

1.

CHECK DTC

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON and wait for 10 seconds.

(d) Turn the Techstream on.

(e) Perform "HEALTH CHECK" and check for current DTCs (See page 2018 - 2020 MY Sienna [11/2017 -        ]; CELLULAR COMMUNICATION: SAFETY CONNECT SYSTEM: HEALTH CHECK ).

Result

Result

Proceed to

DTC B1572 is output

A

DTC B1572 is not output

B
B

CHECK FOR INTERMITTENT PROBLEMS

A

2.

INSPECT MICROPHONE AMPLIFIER ASSEMBLY (TELEPHONE MICROPHONE POWER SOURCE)

(a) Remove the microphone amplifier assembly but do not disconnect the connectors (See page 2016 - 2020 MY Sienna [12/2015 -        ]; LIGHTING (INT): PERSONAL LIGHT: REMOVAL ).

*a

Component with harness connected

(Microphone Amplifier Assembly )

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

T34-1 (MACC) - Body Ground

Ignition switch ACC

4 to 6 V
NG

GO TO STEP 5

OK

3.

CHECK HARNESS AND CONNECTOR (DCM (TELEMATICS TRANSCEIVER) - MICROPHONE AMPLIFIER ASSEMBLY)

(a) Disconnect the D73 DCM (Telematics Transceiver) connector.

(b) Disconnect the T34 microphone amplifier assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D73-34 (MCI+) - T34-2 (MIC+)

Always

Below 1 Ω

D73-35 (MCI-) - T34-4 (MIC-)

Always

Below 1 Ω

D73-34 (MCI+) - Body Ground

Always

10 kΩ or higher

D73-35 (MCI-) - Body Ground

Always

10 kΩ or higher

D73-32 (SGND) - Body Ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

REPLACE MICROPHONE AMPLIFIER ASSEMBLY

(a) Replace the microphone amplifier assembly with a normal one and check if the same problem occurs again.

OK:

The system returns to normal.

OK

END
NG

REPLACE MICROPHONE AMPLIFIER ASSEMBLY

5.

INSPECT DCM (TELEMATICS TRANSCEIVER) (TELEPHONE MICROPHONE POWER SOURCE)

(a) Remove the DCM (Telematics Transceiver) but do not disconnect the connectors (See page 2018 - 2020 MY Sienna [11/2017 -        ]; CELLULAR COMMUNICATION: MAYDAY ECU: REMOVAL ).

*a

Component with harness connected

(DCM (Telematics Transceiver))

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

D73-33 (MCVD) - Body Ground

Ignition switch ACC

4 to 6 V
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR
NG

6.

REPLACE DCM (TELEMATICS TRANSCEIVER)

(a) Replace the DCM (Telematics Transceiver) (See page 2018 - 2020 MY Sienna [11/2017 -        ]; CELLULAR COMMUNICATION: MAYDAY ECU: REMOVAL ).

NOTICE:

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

PERFORM DCM ACTIVATION