DTC B1794: Open in Occupant Classification ECU Battery Positive Line [08/2015 - 08/2019]: Procedure

1. Turn the engine switch on (IG), and wait for at least 60 seconds.
2. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   HINT: 

   • First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
3. Turn the engine switch off.
4. Turn the engine switch on (IG), and wait for at least 60 seconds.
5. Check for DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   OK

   DTC B1794 is not output.

   HINT: 

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

Result: 

OK 

USE SIMULATION METHOD TO CHECK 

(Refer to DIAGNOSIS SYSTEM [08/2015 - ] )

Result: 

NG 

See step  2

1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
3. Check that the connectors are properly connected to the center airbag sensor, occupant classification sensors and occupant classification ECU.

   OK

   Connectors are properly connected.

Result: 

NG 

CONNECT CONNECTOR 

Result: 

OK 

See step  3

1. Disconnect the connector from the occupant classification ECU.
2. Check that the connectors (on the occupant classification ECU side) are not damaged (Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [08/2015 - ] ).

   OK

   Connectors are not deformed or damaged.

Result: 

NG 

REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   a4-1 (+B) - Body ground	Engine switch on (IG)	11 to 14 V
   a4-7 (IG2) - Body ground

3. Turn the engine switch off.
4. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
5. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   a4-3 (GND) - Body ground	Always	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to Occupant Classification ECU)

Result: 

NG 

REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

1. Connect the connectors to the occupant classification ECU.
2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
3. Turn the engine switch on (IG), and wait for at least 60 seconds.
4. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   HINT: 

   • First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
5. Turn the engine switch off.
6. Turn the engine switch on (IG), and wait for at least 60 seconds.
7. Check for DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   OK

   DTC B1794 is not output.

   HINT: 

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

Result: 

OK 

USE SIMULATION METHOD TO CHECK 

(Refer to DIAGNOSIS SYSTEM [08/2015 - ] )

Result: 

NG 

See step  6

1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
3. Replace the occupant classification ECU (Refer to REMOVAL [08/2015 - ] ).

   HINT: 

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

Result: 

NEXT 

See step  7

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
2. Turn the engine switch on (IG).
3. Perform the zero point calibration (Refer to INITIALIZATION [08/2015 - ] ).

   OK

   "Zero Point Calibration is complete." is displayed.

Result: 

NEXT 

See step  8

1. Perform the sensitivity check (Refer to INITIALIZATION [08/2015 - ] ).

   Standard

   27 to 33 kg (59.5 to 72.8 lb)

Result: 

NEXT 

END (OCCUPANT CLASSIFICATION ECU IS DEFECTIVE)