B1794

SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1794: Open in Occupant Classification ECU Battery Positive Line
B1794 - Open in Occupant Classification ECU Battery Positive Line

DESCRIPTION

DTC B1794 is stored when a malfunction is detected in the occupant classification ECU.





HINT
* When DTC B1650/32 is stored as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1794 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

NOTICE:
* When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.
* Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1. CHECK FOR DTC

(a) Turn the ignition switch to ON, and wait for at least 60 seconds.

(b) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
* First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored 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) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.

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.

NG -- CHECK CONNECTION OF CONNECTOR

OK -- USE SIMULATION METHOD TO CHECK Diagnosis System

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 center airbag sensor, occupant classification sensors and occupant classification ECU.

OK:

Connectors are properly connected.

NG -- CONNECT CONNECTOR
OK -- Continue to next step.

3. CHECK CONNECTOR

(a) Disconnect the connector from the occupant classification ECU.

(b) Check that the connectors (on the occupant classification ECU side) are not damaged Diagnosis System.

OK:

Connectors are not deformed or damaged.

NG -- REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (SOURCE VOLTAGE)

(a) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.





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

Standard Voltage:





(c) Turn the ignition switch off.

(d) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

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

Standard Resistance:





Text in Illustration





NG -- REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. CHECK FOR DTC

(a) Connect the connectors to the occupant classification ECU.

(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 the DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
* First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored 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) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.

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.

NG -- REPLACE OCCUPANT CLASSIFICATION ECU

OK -- USE SIMULATION METHOD TO CHECK Diagnosis System

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) Turn the ignition switch to ON.

(c) Perform the zero point calibration Programming and Relearning.

OK:

"Zero Point Calibration is complete." is displayed.

NEXT -- Continue to next step.

8. PERFORM SENSITIVITY CHECK

(a) Perform the sensitivity check Programming and Relearning.

Standard:

27 to 33 kg (59.5 to 72.8 lb)

NEXT -- END (OCCUPANT CLASSIFICATION ECU IS DEFECTIVE)