DTC B1650: Occupant Detection System Malfunction

Diagnosis start condition: 

When the ignition voltage is 10 - 16 V.

DTC detecting condition: 

• Occupant detection sensor is faulty.
• Occupant detection control module is faulty.
• Seat harness is defective.
• Fuse is blown.
• Rear airbag harness is faulty.

Wiring diagram: 

Occupant detection system Ref. to WIRING SYSTEM (IMPREZA MODEL)>OCCUPANT DETECTION SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>OCCUPANT DETECTION SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>OCCUPANT DETECTION SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Read the DTC of [Occupant Detection] using the Subaru Select Monitor. Ref. to OCCUPANT DETECTION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is any DTC other than DTC B1650 displayed? (Current malfunction)

   Yes  : Perform the diagnosis for displayed DTC other than DTC B1650. Ref. to OCCUPANT DETECTION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

   No  : Go to  2.

2. CHECK SEAT HARNESS (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>REPAIR CONTENTS>NOTE>BATTERY .
      NOTE: For the hybrid model, turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery.
   2. Disconnect the connector (AB61) from occupant detection control module.
   3. Disconnect the connector (AB59) of seat harness and rear harness.
   4. Connect the connector (1BB) in the test harness BB to the connector (AB59).
   5. Using a tester, measure the resistance between occupant detection control module connector and connector (2BB) in test harness BB.
      CAUTION: Connect the terminal in test harness BC to connector (AB61) terminal, and apply the tester to test harness BC.

      Connector & terminal 

      (AB61) No. 2 - (2BB) No. 1:

      (AB61) No. 3 - (2BB) No. 2:

   Is the resistance less than 10 Ω?

   Yes  : Go to  3.

   No  : Replace the seat harness. After replacement, if DTC B1650 is displayed. Go to.

3. CHECK SEAT HARNESS (SHORTED BETWEEN LINES AND SHORTED TO GROUND)  .

   Using a tester, measure the resistance between occupant detection control module connector and chassis ground, and between occupant detection control module connector terminals.

   CAUTION: Connect the terminal in test harness BC to connector (AB61) terminal, and apply the tester to test harness BC. Two sets of test harness BC are required.

   Connector & terminal 

   (AB61) No. 2 - All terminals other than (AB61) No. 2:

   (AB61) No. 3 - All terminals other than (AB61) No. 3:

   (AB61) No. 2 - Chassis ground:

   (AB61) No. 3 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes  : Go to  4.

   No  : Replace the seat harness. After repairing, if DTC B1650 is displayed. Go to  4.

4. CHECK SEAT HARNESS (BATTERY SHORT)  .
   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>REPAIR CONTENTS>NOTE>BATTERY .
      NOTE: For the hybrid model, turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery.
   2. Using a tester, measure the voltage between occupant detection control module connector and chassis ground.
      CAUTION: Connect the terminal in test harness BC to connector (AB61) terminal, and apply the tester to test harness BC.

      Connector & terminal 

      (AB61) No. 2 (+) - Chassis ground (-):

      (AB61) No. 3 (+) - Chassis ground (-):

   Is the voltage less than 1 V?

   Yes  : Go to  5.

   No  : Replace the seat harness. After repairing, if DTC B1650 is displayed. Go to  5.

5. CHECK REAR HARNESS (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>REPAIR CONTENTS>NOTE>BATTERY .
      NOTE: For the hybrid model, turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery.
   2. Disconnect the connectors (AB6, AB17, AB18) from airbag control module.
   3. Connect the connector (1AG) in the test harness AG to the connectors (AB6, AB17, AB18).
   4. Connect the connector (1AB) in the test harness AB to the connector (AB53).
   5. Measure the resistance between connector (6AG) in the test harness AG and connector (2AB) in the test harness AB.

      Connector & terminal 

      (2AB) No. 1 - (6AG) No. 9:

      (2AB) No. 2 - (6AG) No. 11:

   Is the resistance less than 10 Ω?

   Yes  : Go to  6.

   No  : Replace the rear harness. After replacement, if DTC B1650 is displayed, replace the airbag Control Module. Ref. to AIRBAG SYSTEM>AIRBAG CONTROL MODULE .

6. CHECK REAR HARNESS (SHORTED BETWEEN LINES AND SHORTED TO GROUND)  .

   Measure the resistance between connector (6AG) in the test harness AG and chassis ground, and between connectors in the test harness AG.

   Connector & terminal 

   (6AG) No. 9 - All terminals in test harness AG (except for (6AG) No. 9):

   (6AG) No. 11 - All terminals in test harness AG (except for (6AG) No. 11):

   (6AG) No. 9 - Chassis ground:

   (6AG) No. 11 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes  : Go to  7.

   No  : Replace the rear harness. After repairing, if DTC B1650 is displayed, replace the airbag Control Module. Ref. to AIRBAG SYSTEM>AIRBAG CONTROL MODULE .

7. CHECK REAR HARNESS (BATTERY SHORT)  .
   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>REPAIR CONTENTS>NOTE>BATTERY .
      NOTE: For the hybrid model, turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery.
   2. Using a tester, measure the voltage between connector (6AG) in test harness AG and chassis ground.

      Connector & terminal 

      (6AG) No. 9 (+) - Chassis ground (-):

      (6AG) No. 11 (+) - Chassis ground (-):

   Is the voltage less than 1 V?

   Yes  : Replace the airbag Control Module. Ref. to AIRBAG SYSTEM>AIRBAG CONTROL MODULE .

   No  : Replace the rear harness. After repairing, if DTC B1650 is displayed, replace the airbag Control Module. Ref. to AIRBAG SYSTEM>AIRBAG CONTROL MODULE .