DTC B2A08: SOS Button Circuit

Diagnosis start condition: 

When ignition switch is ON.

DTC detecting condition: 

The following conditions occur for at least 50 ms.

• SOS button impedance is more than 10 kΩ.
• SOS button is stuck for at least 60 seconds.

Trouble symptom: 

• SOS 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.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Read the DTC of [Telematics] using the Subaru Select Monitor. Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B2A08 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. 

2. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the telematics button connector.
   3. Disconnect the DCM connector.
   4. Measure the resistance between telematics button connector and DCM connector.

      Connector and terminal 

      (i270) No. 5 - (R463) No. 6:

      (R463) No. 1 - Chassis ground:

   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 and terminal 

   (i270) No. 5 - 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 and terminal 

      (i270) No. 5 (+) - Chassis ground (-):

      (R463) No. 1 (+) - 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 THE SOS BUTTON UNIT  .
   1. Turn the ignition switch to OFF.
   2. Measure the resistance of the SOS button unit.

   Terminals 

   No. 6 - No. 1:

   Is the resistance 1 Ω or less when SOS button is ON, and 1.5 - 1.7 kΩ when SOS button is OFF?

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

   No:  Replace the telematics button. Ref. to ENTERTAINMENT & MONITORING>SWITCHES AND HARNESS .