B1793

SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1793: Occupant Classification Sensor Power Supply Circuit Malfunction

DTC B1793 - Occupant Classification Sensor Power Supply Circuit Malfunction

DESCRIPTION

The occupant detection sensor power supply circuit consists of the occupant classification ECU and the occupant detection sensors.
DTC B1793 is stored when a malfunction is detected in the occupant detection sensor power supply circuit.





HINT:
- When DTC B1650/32 is detected as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1793 of the occupant classification system.
- Use the Techstream to check for DTCs of the occupant classification ECU, otherwise the DTCs cannot be read.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTE: After the ignition switch is turned off, the navigation system requires approximately 90 seconds to record various types of memory and settings. As a result, after turning the ignition switch off, wait 90 seconds or more before disconnecting the cable from the negative (-) battery terminal.

HINT:
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front seat RH installation bolts to see the undersurface of the seat cushion.
- In the above case, hold the seat so that it does not fall down. Holding the seat for a long period of time may cause problems, such as seat rail deformation. Hold the seat up only for as long as necessary.

PROCEDURE

1. CHECK FOR DTC
(a) Turn the ignition switch to ON, and wait for at least 60 seconds.
(b) Clear any DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.

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.

(c) Turn the ignition switch off.
(d) Turn the ignition switch to ON, and wait for at least 60 seconds.
(e) Using the Techstream, check for DTCs of the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1793 is not output.

HINT: DTCs other than DTC B1793 may be output at this time, but they are not related to this check.

NG -- CHECK CONNECTION OF CONNECTOR
OK -- USE SIMULATION METHOD TO CHECK
2. CHECK CONNECTION OF CONNECTOR
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Check that the connectors are properly connected to the occupant classification ECU and the occupant detection sensors.
OK:
Connectors are properly connected.

NG -- CONNECT CONNECTORS PROPERLY
OK -- Continue to next step.

3. CHECK CONNECTOR
(a) Check that the connectors (on the occupant classification ECU side and the occupant detection sensors side) are not damaged Electronic Circuit Inspection Procedure.
OK:
Connectors are not deformed or damaged.

NG -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.

4. CHECK FRONT SEAT WIRE RH
(a) Disconnect the connectors from the occupant classification ECU and the 4 occupant detection sensors.




(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
(c) Turn the ignition switch to ON, and wait for at least 60 seconds.
(d) Measure the voltage according to the value(s) in the table below.

Standard Voltage:





(e) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





(f) Turn the ignition switch off.
(g) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(h) Measure the resistance according the value(s) in the table below.

Standard Resistance:





NG -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.

5. CHECK FOR DTC
(a) Connect the connectors to the occupant classification ECU and the 4 occupant detection sensors.
(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
(c) Turn the ignition switch to ON, and wait for at least 60 seconds.
(d) Clear any DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.

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.

(e) Turn the ignition switch off.
(f) Turn the ignition switch to ON, and wait for at least 60 seconds.
(g) Using the Techstream, check for DTCs of the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1793 is not output.

HINT: DTCs other than DTC B1793 may be output at this time, but they are not related to this check.

NG -- REPLACE OCCUPANT CLASSIFICATION ECU
OK -- USE SIMULATION METHOD TO CHECK
6. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Replace the occupant classification ECU Removal.

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

NEXT -- Continue to next step.

7. PERFORM ZERO POINT CALIBRATION
(a) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to ON, and wait for at least 60 seconds.
(d) Using the Techstream, perform the zero point calibration Programming and Relearning.
NEXT -- Continue to next step.

8. PERFORM SENSITIVITY CHECK
(a) Using the Techstream, perform the sensitivity check Programming and Relearning.
Standard range:
27 to 33 kg (59.5 to 72.8 lb)
NEXT -- END