DTC B2A04: Mic Circuit

Diagnosis start condition: 

When ACC is ON.

DTC detecting condition: 

Any of the followings continues for 1 second or more.

• MIC impedance is more than 10 kΩ. (Detached MIC, etc.)
• MIC impedance is less than 10 Ω. (Short-circuited MIC, etc.)

Trouble symptom: 

• Call function cannot be used.
• RED LED illuminates.

Wiring diagram: 

Telematics Ref. to WIRING SYSTEM>TELEMATICS SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .

   Read the DTC of [Telematics] using the Subaru Select Monitor. Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B2A04 displayed? (Current code)

   Yes:  Go to  2.

   No:  Even if DTC is displayed, the circuit has returned to a normal condition at this time.

   Reproduce the failure, and then perform the diagnosis.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the microphone connector.
   3. Disconnect the DCM connector.
   4. Measure the resistance between microphone connector and DCM connector.

      Connector & terminal 

      (Rf11) No. 5 - (i106) No. 8:

      (Rf11) No. 16 - (i106) No. 14:

      (Rf11) No. 7 - (i106) No. 6:

   Is the resistance 1 Ω or less?

   Yes:  Go to  3.

   No:  Repair or replace the open circuit of harness.

3. CHECK HARNESS (GROUND SHORT CIRCUIT)  .

   Measure the resistance between DCM connector and chassis ground.

   Connector & terminal 

   (i106) No. 8 - Chassis ground:

   (i106) No. 14 - Chassis ground:

   (i106) No. 6 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  4.

   No:  Repair or replace the short circuit of the harness.

4. CHECK THE CONNECTOR (SHORT CIRCUIT TO POWER SUPPLY)  .
   1. Turn the ignition switch to ON.
   2. Measure the voltage between DCM connector and chassis ground.

      Connector & terminal 

      (i106) No. 8 (+) - Chassis ground (-):

      (i106) No. 14 (+) - Chassis ground (-):

      (i106) No. 6 (+) - Chassis ground (-):

   Is the voltage less than 1 V?

   Yes:  Go to  5.

   No:  Repair or replace the short circuit of the harness.

5. CHECK MICROPHONE  .
   1. Turn the ignition switch to OFF.
   2. Confirm the microphone voice input.

   Is the check result OK?

   Yes:  Replace the DCM. Ref. to ENTERTAINMENT & MONITORING>DATA COMMUNICATION MODULE .

   No:  Replace the microphone. Ref. to ENTERTAINMENT & MONITORING>MICROPHONE .