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 battery positive line.






WIRING DIAGRAM





INSPECTION PROCEDURE

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, and wait for at least 10 seconds.
(d) Turn the ignition switch to the on position.
(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 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.
OK:
The connectors are properly connected.
NG -- CONNECT CONNECTORS
OK -- Continue to next step.
3. CHECK WIRE HARNESS (SOURCE VOLTAGE)




(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) Disconnect the Q4 connector from the occupant classification ECU.
(d) Connect the negative (-) terminal cable to the battery.
(e) Measure the voltage.
Standard voltage:





(f) Measure the resistance.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - OCCUPANT CLASSIFICATION ECU)
OK -- Continue to next step.
4. CHECK DTC
(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) Connect the connectors to the occupant classification ECU.
(d) Connect the negative (-) terminal cable to the battery.
(e) Turn the ignition switch to the on position.
(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 assembly.
(g) Turn the ignition switch to the lock position, and wait for at least 10 seconds.
(h) Turn the ignition switch to the on position.
(i) Using a 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.
5. REPLACE OCCUPANT CLASSIFICATION ECU
(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) Replace the occupant classification ECU Removal.
HINT: Perform the inspection using parts from a normal vehicle when possible.

NEXT -- Continue to next step.
6. PERFORM ZERO POINT CALIBRATION
(a) Connect the negative (-) terminal cable to the battery.
(b) Connect a Techstream to the DLC3.
(c) Turn the ignition switch to the on position.
(d) Using the Techstream, perform the zero point calibration Programming and Relearning.
OK:
COMPLETED is displayed on the tester.
NEXT -- Continue to next step.
7. PERFORM SENSITIVITY CHECK
(a) Using a Techstream, perform the sensitivity check Programming and Relearning.
(1) Confirm that nothing is placed on the passenger seat.
(2) Confirm that the beginning sensor reading is within the standard range.
Standard range:
-3.2 to 3.2 kg (-7 to 7 lb)
(3) Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.
(4) Confirm that the sensitivity is within the standard range.
Standard range:
27 to 33 kg (59.52 to 72.75 lb)
HINT: When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).

NEXT -- END