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 communication circuit consists of the occupant classification ECU and center airbag sensor.
DTC B1790 is stored when a malfunction is detected in the center airbag sensor communication circuit.
HINT
* When DTC B1650/32 is stored 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
NOTICE:
When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.
HINT
* If troubleshooting (wire harness inspection) is difficult to perform, remove the front RH seat 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 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 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.
OK:
Connectors are properly connected.
NG -- CONNECT CONNECTOR
OK -- Continue to next step.
3. CHECK CONNECTOR
(a) Disconnect the connectors from the center airbag sensor and occupant classification ECU.
(b) Check that the connectors (on the center airbag sensor side and 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 OCCUPANT CLASSIFICATION SYSTEM CIRCUIT
(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) Using a service wire, connect terminals 12 (FSR+) and 13 (FSR-) of connector B.
NOTICE:
Do not forcibly insert the service wire into the terminals of the connector.
(f) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
(g) Disconnect the service wire from connector B.
(h) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- CHECK FRONT SEAT WIRE RH (OCCUPANT CLASSIFICATION ECU - FLOOR WIRE)
OK -- Continue to next step.
5. CHECK FOR DTC
(a) Connect the connectors to the occupant classification ECU and center airbag sensor.
(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 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.
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 -- Continue to next step.
9. CHECK FOR DTC
(a) 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.
(b) Turn the ignition switch off.
(c) Turn the ignition switch to ON, and wait for at least 60 seconds.
(d) Check for DTCs 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 Removal
OK -- END (OCCUPANT CLASSIFICATION ECU IS DEFECTIVE)
10. CHECK FRONT SEAT WIRE RH (OCCUPANT CLASSIFICATION ECU - FLOOR WIRE)
(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) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
(d) Turn the ignition switch off.
(e) Disconnect the connector from the occupant classification ECU.
(f) 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 the connector.
(g) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
(h) Disconnect the service wire from connector E.
(i) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPLACE FRONT SEAT WIRE RH Disassembly
OK -- REPLACE FLOOR WIRE