B1794

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

DTC B1794 - Open in Occupant Classification ECU Battery Positive Line

DESCRIPTION

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





HINT:
- When DTC B1650/32 is detected as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1794 of the occupant classification system.
- Use a Techstream to check for DTCs of the occupant classification ECU, otherwise the DTCs cannot be read.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK FOR DTC
(a) Turn the ignition switch 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 a Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
(c) Turn the ignition switch off, and wait for at least 10 seconds.
(d) Turn the ignition switch 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 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
2. CHECK CONNECTION OF CONNECTOR
(a) Turn the ignition switch off.
(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 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) Check that the connectors (on the occupant classification ECU side) are not damaged Electronic Circuit Inspection Procedure.
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) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Disconnect the connector from the occupant classification ECU.
(d) Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
(e) Turn the ignition switch ON, and wait for at least 60 seconds.
(f) Measure the resistance and voltage according to the value(s) in the table below.
Standard resistance:






Standard voltage:






NG -- REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. CHECK FOR DTC
(a) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Connect the connectors to the occupant classification ECU.
(d) Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
(e) Turn the ignition switch ON, and wait for at least 60 seconds.
(f) 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 a Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
(g) Turn the ignition switch off, and wait for at least 10 seconds.
(h) Turn the ignition switch ON, and wait for at least 60 seconds.
(i) Using the Techstream, check for DTCs of the occupant classification ECU 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
6. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, 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 negative (-) terminal cable to the battery, and wait for at least 2 seconds.
(b) Connect a Techstream to the DLC3.
(c) Turn the ignition switch 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 a Techstream, perform the sensitivity check Programming and Relearning.
Standard range:
27 to 33 kg (59.5 to 72.8 lb)
NEXT -- END