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Home >> Subaru >> 2023 >> Outback Touring XT >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Air Bag System (Diagnostics) (1 Of 2) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC B1657: Crash Detected Signal Communication

DTC B1657: Crash Detected Signal Communication

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

Communication with body integrated unit is faulty

Wiring diagram: 

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

G16390673Courtesy of SUBARU OF AMERICA, INC.
CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to AIRBAG (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .
  1. CHECK POOR CONTACT OF CONNECTORS  .

    Check for poor contact of the connectors (AB42, i83) between the airbag control module and body integrated unit.

    Is there poor contact?

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

    No:  Go to  2.

  2. CHECK AIRBAG MAIN HARNESS (BETWEEN AIRBAG CONTROL MODULE AND BODY INTEGRATED UNIT) (OPEN CIRCUIT)  .
    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. Remove the instrument panel lower cover and column cover, and disconnect the connector (AB46).
    3. Disconnect the passenger's airbag module connectors (AB83) and (AB84).
    4. Disconnect the connector (AB86) from the driver's knee airbag module.
    5. Disconnect the connectors (AB41, AB42, AB43) from airbag control module.
    6. Connect the connector (1BF) in the test harness BF to the connectors (AB41, AB42, AB43).
    7. Disconnect the connector (i83) from body integrated unit.
    8. Measure the resistance between connector (2BF) in test harness BF and body integrated unit connector (i83).

      Connector & terminal 

      (2BF) No. 8 - (i83) No. 31:

    Is the resistance less than 10 Ω?

    Yes:  Go to  3.

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

  3. CHECK AIRBAG REAR HARNESS (BETWEEN AIRBAG CONTROL MODULE AND BODY INTEGRATED UNIT) (SHORTED TO GROUND)  .

    Measure the resistance between connector (2BF) in the test harness BF and chassis ground.

    Connector & terminal 

    (2BF) No. 8 - Chassis ground:

    Is the resistance 1 MΩ or more?

    Yes:  Go to  4.

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

  4. REPLACE BODY INTEGRATED UNIT AND CHECK AIRBAG CONTROL MODULE AFTER REPLACEMENT  .
    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. Replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .
    3. Disconnect all test harnesses.
    4. Connect all connectors.
    5. Install the ground terminal to the battery sensor and turn the ignition switch to ON. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
    6. Using the Subaru Select Monitor, perform the clear memory of [Airbag]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
    7. Execute the inspection mode. Ref. to AIRBAG (DIAGNOSTICS)>INSPECTION MODE .
    8. Read the DTC of [Airbag] using the Subaru Select Monitor. Ref. to AIRBAG (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC B1657 displayed? (Current code)

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

    No:  Go to  5.

  5. CHECK FOR ANY OTHER DTC ON DISPLAY  .

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

    Is any other DTC displayed? (Current code)

    Yes:  Perform the diagnosis for other displayed DTCs. Ref. to AIRBAG (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

    No:  Finish the diagnosis.

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