B1793

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

DTC B1793 - Occupant Classification Sensor Power Supply Circuit Malfunction

DESCRIPTION

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





HINT: When DTC B1150/23 is detected as a result of troubleshooting for the supplemental restraint system, perform troubleshooting for DTC B1793 of the occupant classification system.

WIRING DIAGRAM





INSPECTION PROCEDURE

HINT:
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see the under surface 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 a problem, such as seat rail deformation. Hold the seat only as necessary.

PROCEDURE

1. CHECK DTC
(a) Turn the ignition switch to the ON position.
(b) Clear the 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 assembly.

(c) Turn the ignition switch to the LOCK position.
(d) Turn the ignition switch to the ON position.
(e) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1793 is not output.

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

OK -- USE SIMULATION METHOD TO CHECK

NG -- Continue to next step.

2. CHECK CONNECTION OF CONNECTORS
(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Check that the connectors are properly connected to the occupant classification ECU and the occupant classification sensors.
OK:
The connectors are properly connected.

NG -- CONNECT CONNECTORS, THEN GO TO STEP 1
OK -- Continue to next step.

3. CHECK SEAT WIRE NO. 1 (SHORT TO B+)




(a) Disconnect the connectors from the occupant classification ECU and the 4 occupant classification sensors.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the ignition switch to the ON position.
(d) Measure the voltage according to the value(s) in the table below.
Voltage:





NG -- REPAIR OR REPLACE SEAT WIRE NO. 1
OK -- Continue to next step.

4. CHECK SEAT WIRE NO. 1 (SHORT TO GROUND)




(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Measure the resistance according to the value(s) in the table below.
Resistance:





NG -- REPAIR OR REPLACE SEAT WIRE NO. 1
OK -- Continue to next step.

5. CHECK SEAT WIRE NO. 1 (OPEN)




(a) Measure the resistance according to the value(s) in the table below.
Resistance:





NG -- REPAIR OR REPLACE SEAT WIRE NO. 1
OK -- Continue to next step.

6. CHECK SEAT WIRE NO. 1 (SHORT)




(a) Measure the resistance according to the value(s) in the table below.
Resistance:





NG -- REPAIR OR REPLACE SEAT WIRE NO. 1
OK -- Continue to next step.

7. CHECK DTC
(a) Connect the connectors to the occupant classification ECU and the 4 occupant classification sensors.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the ignition switch to the ON position.
(d) Clear the 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 assembly.

(e) Turn the ignition switch to the LOCK position.
(f) Turn the ignition switch to the ON position.
(g) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1793 is not output.

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

OK -- USE SIMULATION METHOD TO CHECK

NG -- Continue to next step.

8. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the negative (-) terminal cable from the battery.
(c) Replace the occupant classification ECU Removal.

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

NEXT -- Continue to next step.

9. PERFORM ZERO POINT CALIBRATION
(a) Connect the negative (-) terminal cable to the battery.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the Techstream, perform "Zero point calibration" Programming and Relearning.
OK:
"Zero Point Calibration is Complete." is displayed.

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

10. PERFORM SENSITIVITY CHECK
(a) Using the Techstream, perform "Sensitivity check" Programming and Relearning.
Standard value:
27 to 33 kg (59.52 to 72.75 lb)

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

11. CHECK DTC
(a) Connect the negative (-) terminal cable to the battery.
(b) Turn the ignition switch to the ON position.
(c) Clear the 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 assembly.

(d) Turn the ignition switch to the LOCK position.
(e) Turn the ignition switch to the ON position.
(f) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1793 is not output.

HINT: Codes other than DTC B1793 may be output at this time, but they are related to this check.

OK -- END

NG -- Continue to next step.

12. REPLACE FRONT SEAT ASSEMBLY RH
(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the negative (-) terminal cable from the battery.
(c) Replace the front seat assembly RH Removal for manual seat, Removal for power seat).
NEXT -- Continue to next step.

13. PERFORM ZERO POINT CALIBRATION
(a) Connect the negative (-) terminal cable to the battery.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the Techstream, perform "Zero point calibration" Programming and Relearning.
OK:
"Zero Point Calibration is Complete." is displayed.
NEXT -- Continue to next step.

14. PERFORM SENSITIVITY CHECK
(a) Using the Techstream, perform "Sensitivity check" Programming and Relearning.
Standard value:
27 to 33 kg (59.52 to 72.75 lb)
NEXT -- END