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

CHECK FOR DTC
1. Turn the ignition switch to ON.
2. Clear the DTCs.Refer to DTC CHECK / CLEAR .
  HINT:
  
  First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
3. Turn the ignition switch off, and wait for at least 10 seconds.
4. Turn the ignition switch to ON.
5. Check the DTCs.Refer to DTC 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 → USE SIMULATION METHOD TO CHECK

NG: Go to next step
CHECK FUSE (ECU-B)
1. Check the ECU-B fuse.
  Standard resistance
  
  Below 1Ω
NG → REPLACE FUSE

OK: Go to next step
CHECK CONNECTION OF CONNECTOR
1. Turn the ignition 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 occupant classification ECU.
  OK
  
  The connectors are properly connected.
NG → CONNECT CONNECTOR

OK: Go to next step

CHECK WIRE HARNESS (SOURCE VOLTAGE)

Fig 1: Checking Wire Harness (Source Voltage)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Turn the ignition switch off.
Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
Disconnect the L1 connector from the occupant classification ECU.
Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

Measure the voltage of the wire harness side connector.

Standard voltage

Tester Connection	Condition	Specified Condition
L1-1 (+B) - Body ground	Always	11 to 14 V
L1-7 (IG) - Body ground	Ignition switch ON	11 to 14 V

Turn the ignition switch off.

Measure the resistance of the wire harness side connector.

Standard resistance

Tester Connection	Specified Condition
L1-3 (GND) - Body ground	Below 1 Ω

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

OK: Go to next step

CHECK FOR DTC
1. Turn the ignition 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 ignition switch to ON.
6. Clear the DTCs.Refer to DTC CHECK / CLEAR .
  HINT:
  
  First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
7. Turn the ignition switch off, and wait for at least 10 seconds.
8. Turn the ignition switch to ON.
9. Using the Techstream, check for DTCs of the occupant classification ECU.Refer to DTC 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 → USE SIMULATION METHOD TO CHECK

NG: Go to next step
REPLACE OCCUPANT CLASSIFICATION ECU
1. Turn the ignition 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 COMPONENTS .
NEXT: Go to next step
PERFORM ZERO POINT CALIBRATION
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 ignition switch to ON.
4. Using the Techstream, perform the zero point calibration.Refer to INITIALIZATION .
  OK
  
  "Zero Point Calibration is complete." is displayed.
NEXT: Go to next step
PERFORM SENSITIVITY CHECK
1. Using the Techstream, perform the sensitivity check.Refer to INITIALIZATION .
  Standard value
  
  27 to 33 kg (59.52 to 72.75 lb)
NEXT → END