B1790

SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1790: Center Airbag Sensor Assembly Communication Circuit Malfunction
B1790 - Center Airbag Sensor Assembly Communication Circuit Malfunction

DESCRIPTION

The center airbag sensor assembly communication circuit consists of the occupant classification ECU and the center airbag sensor assembly.

DTC B1790 is stored when a malfunction is detected in the center airbag sensor assembly communication circuit.

HINT
* When DTC B1650/32 is detected as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1790 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

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

PROCEDURE

1. CHECK FOR DTC

(a) Turn the ignition switch to 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 assembly.
* 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) Using the Techstream, check for DTCs of the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.

OK:

DTC B1790 is not output.

HINT
DTCs other than DTC B1790 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 occupant classification ECU and center airbag sensor assembly. Also check that the connectors that link the front seat wire RH and floor wire are properly connected.

OK:

Connectors are properly connected.

NG -- CONNECT CONNECTORS PROPERLY
OK -- Continue to next step.

3. CHECK CONNECTOR

(a) Check that the connectors (on the center airbag sensor assembly side, occupant classification ECU side, front seat wire RH side and floor wire side) are not damaged.

OK:

Connectors are not deformed or damaged.

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

4. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT

Text in Illustration

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

(b) Turn the ignition switch to ON.

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

Standard Voltage:

(d) Turn the ignition switch off.

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

(f) Using a service wire, connect terminals 16 (FSR+) and 24 (FSR-) of connector B.

NOTICE:
Do not forcibly insert the service wire into the terminals of the connector.

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

Standard Resistance:

(h) Disconnect the service wire from connector B.

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

Standard Resistance:

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

5. CHECK FOR DTC

(a) Connect the connectors to the occupant classification ECU and the center airbag sensor assembly.

(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 any DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.

HINT
* First clear any DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
* 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) Using the Techstream, check for DTCs of the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.

OK:

DTC B1790 is not output.

HINT
DTCs other than DTC B1790 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.

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

NEXT -- Continue to next step.

7. CHECK FOR DTC

(a) Turn the ignition switch to 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 any DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
* 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) Using the Techstream, check for DTCs of the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.

OK:

DTC B1790 is not output.

HINT
DTCs other than DTC B1790 may be output at this time, but they are not related to this check.

NG -- REPLACE CENTER AIRBAG SENSOR ASSEMBLY
OK -- Continue to next step.

8. PERFORM ZERO POINT CALIBRATION

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Using the Techstream, perform the zero point calibration Programming and Relearning.

NEXT -- Continue to next step.

9. PERFORM SENSITIVITY CHECK

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

Standard range:

27 to 33 kg (59.5 to 72.8 lb)

NEXT -- END

10. REPLACE CENTER AIRBAG SENSOR ASSEMBLY

(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 center airbag sensor assembly Removal.

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

NEXT -- END

11. CHECK FRONT SEAT WIRE RH

Text in Illustration

(a) Disconnect the front seat wire RH connector from the floor wire.

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

(c) Turn the ignition switch to ON.

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

Standard Voltage:

(e) Turn the ignition switch off.

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

(g) Using a service wire, connect terminals 8 (FSR+) and 4 (FSR-) of connector E.

NOTICE:
Do not forcibly insert the service wire into the terminals of connector.

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

Standard Resistance:

(i) Disconnect the service wire from connector E.

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

Standard Resistance:

NG -- REPLACE FRONT SEAT WIRE RH Disassembly

OK -- REPLACE FLOOR WIRE