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

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

   HINT: 

   • First clear DTCs stored in the occupant classification ECU and then 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, and wait for at least 10 seconds.
4. Turn the engine switch on (IG), and wait for at least 60 seconds.
5. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [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 [08/2019 - ] )

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 detection sensors and occupant classification ECU.

   OK

   Connectors are properly connected.

Result: 

NG 

CONNECT CONNECTORS PROPERLY 

Result: 

OK 

See step  3

1. Check that the connectors (on the occupant classification ECU side) are not damaged (Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [08/2019 - ] ).

   OK

   Connectors are not deformed or damaged.

Result: 

NG 

REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Turn the engine switch off.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
3. Disconnect the W6*1 or P14*2 ECU connector.

   HINT: 

   *1: for Power Seat

   *2: for Manual Seat

4. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
5. Turn the engine switch on (IG), and wait for at least 60 seconds.
6. Measure the resistance and voltage according to the value(s) in the table below.

   Standard Resistance

   FOR POWER SEAT
   
   

   Tester Connection	Condition	Specified Condition
   W6-3 (GND) - Body ground	Always	Below 1 Ω

   FOR MANUAL SEAT
   
   

   Tester Connection	Condition	Specified Condition
   P14-3 (GND) - Body ground	Always	Below 1 Ω

   Standard Voltage

   FOR POWER SEAT
   
   

   Tester Connection	Switch Condition	Specified Condition
   W6-1 (+B) - Body ground	Engine switch on (IG)	11 to 14 V
   W6-7 (IG) - Body ground

   FOR MANUAL SEAT
   
   

   Tester Connection	Switch Condition	Specified Condition
   P14-1 (+B) - Body ground	Engine switch on (IG)	11 to 14 V
   P14-7 (IG) - Body ground

Result: 

NG 

REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
3. Connect the connectors to the occupant classification ECU.
4. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
5. Turn the engine switch on (IG), and wait for at least 60 seconds.
6. Clear any DTCs stored in the memory (Refer to DTC CHECK / CLEAR [08/2019 - ] ).

   HINT: 

   • First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
7. Turn the engine switch off, and wait for at least 10 seconds.
8. Turn the engine switch on (IG), and wait for at least 60 seconds.
9. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [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 [08/2019 - ] )

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 [08/2019 - ] ).

   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. Connect the Techstream to the DLC3.
3. Turn the engine switch on (IG), and wait for at least 60 seconds.
4. Using the Techstream, perform the zero point calibration (Refer to INITIALIZATION [08/2019 - ] ).

Result: 

NEXT 

See step  8

1. Using the Techstream, perform the sensitivity check (Refer to INITIALIZATION [08/2019 - ] ).

   Standard range

   27 to 33 kg (59.5 to 72.8 lb)

Result: 

NEXT 

END