B1794

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

DESCRIPTION

This circuit consists of the occupant classification ECU and the power source circuit (battery, fuse, wire harness).

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

HINT
When DTC B1794 is output after switching the ignition switch off / ON / off 50 times in a row when a malfunction occurs in the power circuit for the occupant classification system, the DTC is output again when a malfunction is detected even once after being cleared, unless the normal system code is input.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK FOR DTC

(a) Turn the ignition switch to ON.

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

HINT
First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.

(c) Turn the ignition switch off, and wait for at least 10 seconds.

(d) Turn the ignition switch to ON.

(e) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.

OK:

DTC B1794 is not output.

HINT
DTCs other than B1794 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 FUSE (ECU-B)

(a) Check the ECU-B fuse.

Standard resistance:

Below 1Ohms

NG -- REPLACE FUSE
OK -- Continue to next step.

3. 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.

OK:

The connectors are properly connected.

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

4. CHECK WIRE HARNESS (SOURCE VOLTAGE)





(a) Turn the ignition switch off.

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

(c) Disconnect the L1 connector from the occupant classification ECU.

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

(e) Measure the voltage of the wire harness side connector.

Standard voltage:





(f) Turn the ignition switch off.

(g) Measure the resistance of the wire harness side connector.

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR (BATTERY - OCCUPANT CLASSIFICATION ECU)
OK -- Continue to next step.

5. CHECK FOR DTC

(a) Turn the ignition switch off.

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

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

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

(e) Turn the ignition switch to ON.

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

HINT
First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.

(g) Turn the ignition switch off, and wait for at least 10 seconds.

(h) Turn the ignition switch to ON.

(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 B1794 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.

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 Components.

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.

(d) Using the Techstream, 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) Using the Techstream, perform the sensitivity check Programming and Relearning.

Standard value:

27 to 33 kg (59.52 to 72.75 lb)

NEXT -- END