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.

• The SOS button impedance is more than 10 KΩ for at least 50 ms.
• 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>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 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 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. Using a tester, measure the resistance between the DCM connector and telematics button connector and between the telematics button connector and chassis ground.

      Connector & terminal 

      (i105) No. 5 - (Rf32) No. 6:

      (Rf32) 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)  .

   Using a tester, measure the resistance between DCM connector and chassis ground.

   Connector & terminal 

   (i105) 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/telematics button connector and chassis ground.

      Connector & terminal 

      (i105) No. 5 (+) - Chassis ground (-):

      (Rf32) 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 .