DTC B1870: Short In Front Seat Cushion Airbag RH

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

Shorted between +/- lines (shorted between rear harness lines, shorted between front seat cushion airbag RH lines, shorted between airbag control module internal lines)

Failure detection pattern: 

• "Primary" (high-priority diagnosis)

Warning light/indicator light: 

• Airbag warning light◦

Wiring diagram: 

Airbag system Ref. to WIRING SYSTEM>AIRBAG SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK POOR CONTACT OF CONNECTORS  .

   Check for poor contact of the connectors between the airbag control module and the seat cushion airbag module RH.

   Is there poor contact?

   Yes:  Replace the airbag rear harness along with body harness.

   No:  GO TO  2.

2. CHECK SEAT CUSHION AIRBAG MODULE  .
   1. Turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery sensor. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
   2. Disconnect the connector (AB89) from the seat cushion airbag module RH, and connect the connector (1D) in the test harness D to connector (AB89).
   3. Connect the airbag resistor to connector (3D) in the test harness D.
   4. Install the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
   5. Execute the inspection mode. Ref. to AIRBAG (DIAGNOSTICS)>INSPECTION MODE .
   6. Read the DTC of [Airbag] using the Subaru Select Monitor. Ref. to AIRBAG (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1870 displayed? (Current code)

   Yes:  GO TO  3.

   No:  Replace the seat cushion airbag module RH. Ref. to AIRBAG SYSTEM>SEAT CUSHION AIRBAG MODULE .

3. CHECK AIRBAG REAR HARNESS (SEAT CUSHION AIRBAG MODULE HARNESS RH) (SHORTED BETWEEN LINES)  .
   1. Turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery sensor. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
   2. Disconnect the connector (AB93) from seat belt pretensioner RH.
   3. Disconnect the connector (AB99) from Rear seatbelt pretensioner RH.
   4. Disconnect the connector (AB87) from side airbag module RH.
   5. Disconnect the connector (AB91) from curtain airbag module RH.
   6. Disconnect the airbag resistor from test harness D.
   7. Disconnect the connectors (AB41, AB42, AB43) from airbag control module.
   8. Connect the connector (1BF) in the test harness BF to the connectors (AB41, AB42, AB43).
   9. Measure the resistance between connector (3D) terminals in test harness D.

      Connector & terminal 

      (3D) No. 3 - (3D) No. 4:

   Is the resistance 1 MΩ or more?

   Yes:  Replace the airbag control module. Ref. to AIRBAG SYSTEM>AIRBAG CONTROL MODULE>REMOVAL .

   No:  Replace the airbag rear harness along with body harness.