From 08/2009

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

DESCRIPTION

The occupant classification sensor power supply circuit consists of the occupant classification ECU and occupant classification sensors.

DTC B1793 is stored when a malfunction is detected in the occupant classification sensor power supply circuit.





HINT
When DTC B1650/32 is detected as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant classification ECU. When DTC B1793 is output, perform troubleshooting for the DTC.

WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
* If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see under the seat cushion.
* In the above case, hold the seat so that it does not fall down. Hold the seat only as necessary because holding the seat for a long period of time may cause seat rail deformation.
PROCEDURE

1. CHECK CONNECTORS

(a) Turn the engine switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

(c) Check that the connectors are properly connected to the 4 occupant classification sensors and occupant classification ECU.

OK:

The connectors are properly connected.

HINT
If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

(d) Disconnect the connectors from the 4 occupant classification sensor and occupant classification ECU.

(e) Check that the terminals of connectors are not damaged.

OK:

The terminals are not deformed or damaged.

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

2. CHECK FRONT SEAT WIRE RH (SHORT TO B+)

(a) Connect the cable to the negative (-) battery terminal.





(b) Turn the engine switch on (IG).

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

Standard Voltage:





Text in Illustration





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

3. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)

(a) Turn the engine switch off.





(b) Disconnect the cable from the negative (-) battery terminal.

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

Standard Resistance:





Text in Illustration





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

4. CHECK FRONT SEAT WIRE RH (OPEN)

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





Standard Resistance:





Text in Illustration





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

5. CHECK FRONT SEAT WIRE RH (SHORT)

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





Standard Resistance:





Text in Illustration





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

6. CHECK DTC

(a) Connect the connectors to the occupant classification ECU and 4 occupant classification sensors.

(b) Connect the cable to the negative (-) battery terminal.

(c) Turn the engine switch on (IG).

(d) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.

(e) Clear the DTCs stored in the center airbag sensor assembly DTC Check / Clear.

(f) Turn the engine switch off.

(g) Turn the engine switch on (IG).

(h) Check for 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.

NG -- REPLACE OCCUPANT CLASSIFICATION ECU

OK -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

7. REPLACE OCCUPANT CLASSIFICATION ECU

(a) Turn the engine switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

(c) Replace the occupant classification ECU Removal.

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

NEXT -- Continue to next step.

8. PERFORM ZERO POINT CALIBRATION

(a) Connect the cable to the negative (-) battery terminal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(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.

9. PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check Programming and Relearning.

Standard:

27 to 33 kg (59.5 to 72.8 lb)

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

10. CHECK DTC

(a) Turn the engine switch on (IG).

(b) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.

(c) Clear the DTCs stored in the center airbag sensor assembly DTC Check / Clear.

(d) Turn the engine switch off.

(e) Turn the engine switch on (IG).

(f) Check for 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.

NG -- REPLACE FRONT SEAT ASSEMBLY RH

OK -- END

11. REPLACE FRONT SEAT ASSEMBLY RH

(a) Turn the engine switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

(c) Replace the front seat assembly RH Removal.

NEXT -- Continue to next step.

12. PERFORM ZERO POINT CALIBRATION

(a) Connect the cable to the negative (-) battery terminal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Using the Techstream, perform Zero Point Calibration Programming and Relearning.

OK:

"Zero Point Calibration is complete." is displayed.

NEXT -- Continue to next step.

13. PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check Programming and Relearning.

Standard:

27 to 33 kg (59.5 to 72.8 lb)

NEXT -- END