DTC B1794: Open in Occupant Classification ECU Battery Positive Line: Procedure

1. Turn the ignition switch to the on position.
2. Clear the DTCs stored in the memory. Refer toDTC CHECK / CLEAR .

   HINT: 

   First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.

3. Turn the ignition switch to the lock position, and wait for at least 10 seconds.
4. Turn the ignition switch to the on position.
5. Check the DTCs. Refer toDTC CHECK / CLEAR .

   OK

   DTC B1794 is not output.

   HINT: 

   DTCs other than B1794 may be output at this time, but they are not related to this check.

OK → See step   8 

NG: Go to next step 

1. Turn the ignition switch to the lock position.
2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
3. Check that the connectors are properly connected to the occupant classification ECU.

   OK

   The connectors are properly connected.

NG → CONNECT CONNECTORS 

OK: Go to next step 

Fig 1: Checking Wire Harness (Source Voltage)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Turn the ignition switch to the lock position.
2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
3. Disconnect the Q4 connector from the occupant classification ECU.
4. Connect the negative (-) terminal cable to the battery.
5. Measure the voltage.

   Standard voltage

   Tester Connection	Condition	Specified Condition
   Q4-1 (+B) - Body ground	Always	11 to 14 V
   Q4-7 (IG) - Body ground	Ignition switch on	11 to 14 V

6. Measure the resistance.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   Q4-3 (GND) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - OCCUPANT CLASSIFICATION ECU) 

OK: Go to next step 

1. Turn the ignition switch to the lock position.
2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
3. Connect the connectors to the occupant classification ECU.
4. Connect the negative (-) terminal cable to the battery.
5. Turn the ignition switch to the on position.
6. Clear any DTCs stored in the memory. Refer toDTC CHECK / CLEAR .

   HINT: 

   First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.

7. Turn the ignition switch to the lock position, and wait for at least 10 seconds.
8. Turn the ignition switch to the on position.
9. Using a Techstream, check for DTCs of the occupant classification ECU. Refer toDTC CHECK / CLEAR .

   OK

   DTC B1794 is not output.

   HINT: 

   DTCs other than B1794 may be output at this time, but they are not related to this check.

OK → See step   8 

NG: Go to next step 

1. Turn the ignition switch to the lock position.
2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
3. Replace the occupant classification ECU. Refer toREMOVAL .

   HINT: 

   Perform the inspection using parts from a normal vehicle when possible.

NEXT: Go to next step 

1. Connect the negative (-) terminal cable to the battery.
2. Connect a Techstream to the DLC3.
3. Turn the ignition switch to the on position.
4. Using the Techstream, perform the zero point calibration. Refer toINITIALIZATION .

   OK

   COMPLETED is displayed on the tester.

NEXT: Go to next step 

1. Using a Techstream, perform the sensitivity check. Refer toINITIALIZATION .
   1. Confirm that nothing is placed on the passenger seat.
   2. Confirm that the beginning sensor reading is within the standard range.

      Standard range

      -3.2 to 3.2 kg (-7 to 7 lb)

   3. Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.
   4. Confirm that the sensitivity is within the standard range.

      Standard range

      27 to 33 kg (59.52 to 72.75 lb)

      HINT: 

      When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).

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