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 Ω (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 (IMPREZA MODEL)>TELEMATICS SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>TELEMATICS SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>TELEMATICS SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

After the Data Communication Module is replaced, registrations of COMM Check and immobilizer system are required. Ref. to ENTERTAINMENT & MONITORING>TELEMATICS SYSTEM>OPERATION>REGISTRATION (COMM CHECK) .
Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .

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 malfunction)

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 again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK HARNESS (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the microphone connector.
3. Disconnect the Data Communication Module connector.
4. Measure the resistance between microphone connector and Data Communication Module connector.
  Connector & terminal
  
  (R405) No. 5 - (i271) No. 8:
  
  (R405) No. 16 - (i271) No. 14:
  
  (R405) No. 7 - (i271) No. 6:
  
  Is the resistance 1 Ω or less?
  
  Yes : Go to 3.
  
  No : Repair or replace the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
Measure the resistance between Data Communication Module connector and chassis ground.

Connector & terminal

(i271) No. 8 - Chassis ground:

(i271) No. 14 - Chassis ground:

(i271) 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.
CHECK THE CONNECTOR (SHORT CIRCUIT TO POWER SUPPLY) .
1. Turn the ignition switch to ON.
2. Measure the voltage between Data Communication Module connector and chassis ground.
  Connector & terminal
  
  (i271) No. 8 (+) - Chassis ground (-):
  
  (i271) No. 14 (+) - Chassis ground (-):
  
  (i271) 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.
CHECK MICROPHONE .
1. Turn the ignition switch to OFF.
2. Confirm the microphone voice input.
  Is the check result OK?
  
  Yes : Replace the Data Communication Module. Ref. to ENTERTAINMENT & MONITORING>DATA COMMUNICATION MODULE .
  
  No : Replace the microphone. Ref. to ENTERTAINMENT & MONITORING>MICROPHONE .