Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001BH83
Model Year Start: 2019 Model: GR Corolla Prod Date Range: [06/2018 - 09/2019]
Title: CELLULAR COMMUNICATION: SAFETY CONNECT SYSTEM (for Gasoline Model): B1572; Telephone Microphone Error; 2019 - 2020 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 09/2019]

DTC

B1572

Telephone Microphone Error

DESCRIPTION

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

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B1572

Telephone Microphone Error

Current of MCVD reaches malfunction criteria for 10 seconds while engine switch is on (IG).

  • Wire harness or connector
  • Telephone microphone assembly
  • Map light assembly
  • DCM (Telematics Transceiver)

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

Before performing this diagnostic procedure, make sure to perform Health Check and confirm that the DCM/VIN registration information is correct.

Click here 2019 - 2020 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 09/2019]; CELLULAR COMMUNICATION: SAFETY CONNECT SYSTEM (for Gasoline Model): HEALTH CHECK

PROCEDURE

1.

CHECK DTC

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG) and wait for 10 seconds.

(d) Turn the Techstream on.

(e) Clear the DTCs.

Body Electrical > Telematics > Clear DTCs

(f) Recheck for DTCs.

Body Electrical > Telematics > Trouble Codes

Result

Proceed to

DTC B1572 is output

A

DTC B1572 is not output

B

B

CHECK FOR INTERMITTENT PROBLEMS

A

2.

INSPECT MAP LIGHT ASSEMBLY (TELEPHONE MICROPHONE ASSEMBLY POWER SOURCE)

(a) Remove the map light assembly but do not disconnect the connectors.

Click here 2019 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 09/2022]; CELLULAR COMMUNICATION: MANUAL(SOS)SWITCH: REMOVAL

*a

Component with harness connected

(Map Light Assembly)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

T6-7 (MACC) - Body ground

Engine switch on (ACC)

4 to 6 V

Standard Resistance:

Tester Connection

Condition

Specified Condition

T6-5 (MCO-) - Body ground

Always

Below 1 Ω

NG

GO TO STEP 5

OK

3.

CHECK HARNESS AND CONNECTOR (DCM (TELEMATICS TRANSCEIVER) - MAP LIGHT ASSEMBLY)

(a) Disconnect the I72 DCM (Telematics Transceiver) connector.

(b) Disconnect the T6 map light assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I72-34 (MCI+) - T6-6 (MCO+)

Always

Below 1 Ω

I72-34 (MCI+) or T6-6 (MCO+) - Body ground

Always

10 kΩ or higher

I72-35 (MCI-) - T6-5 (MCO-)

Always

Below 1 Ω

I72-35 (MCI-) or T6-5 (MCO-) - Body ground

Always

10 kΩ or higher

I72-32 (SGND) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

REPLACE TELEPHONE MICROPHONE ASSEMBLY

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

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; AUDIO / VIDEO: MICROPHONE: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 09/2022]; AUDIO / VIDEO: MICROPHONE: REMOVAL

OK:

The system returns to normal.

OK

END

NG

REPLACE MAP LIGHT ASSEMBLY

5.

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

(a) Remove the DCM (Telematics Transceiver) but do not disconnect the connectors.

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; CELLULAR COMMUNICATION: DCM(TELEMATICS TRANSCEIVER): REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 09/2019]; CELLULAR COMMUNICATION: DCM(TELEMATICS TRANSCEIVER): REMOVAL

*a

Component with harness connected

(DCM (Telematics Transceiver))

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

I72-33 (MCVD) - Body ground

Engine switch on (ACC)

4 to 6 V

Standard Resistance:

Tester Connection

Condition

Specified Condition

I72-35 (MCI-) - Body ground

Always

Below 1 Ω

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR

NG

6.

REPLACE DCM (TELEMATICS TRANSCEIVER)

(a) Replace the DCM (Telematics Transceiver).

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; CELLULAR COMMUNICATION: DCM(TELEMATICS TRANSCEIVER): REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 09/2019]; CELLULAR COMMUNICATION: DCM(TELEMATICS TRANSCEIVER): REMOVAL

NOTICE:

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

PERFORM DCM ACTIVATION