B1790
SUPPLEMENTAL RESTRAINT SYSTEM: OCCUPANT CLASSIFICATION SYSTEM: B1790: Center Airbag Sensor Assembly Communication Circuit Malfunction
DTC 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 recorded when a malfunction is detected in the center airbag sensor assembly communication circuit.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see the under surface 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 a problem, such as seat rail deformation. Hold the seat only as necessary.
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.
(d) Turn the ignition switch to the ON position.
(e) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1790 is not output.
HINT: Codes other than DTC B1790 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.
(c) Check that the connectors are properly connected to the occupant classification ECU and the center airbag sensor assembly.
OK:
The connectors are properly connected.
NG -- CONNECT CONNECTORS, THEN GO TO STEP 1
OK -- Continue to next step.
3. CHECK OCCUPANT CLASSIFICATION ECU CIRCUIT (SHORT TO B+)
(a) Disconnect the connectors from the occupant classification ECU and the center airbag sensor assembly.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the ignition switch to the ON position.
(d) Measure the voltage according to the value(s) in the table below.
Voltage:
NG -- CHECK FLOOR WIRE (SHORT TO B+)
OK -- Continue to next step.
4. CHECK OCCUPANT CLASSIFICATION ECU CIRCUIT (OPEN)
(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) Using a service wire, connect A33-1 (FSR+) and A33-2 (FSR-) of connector "B".
NOTE: Do not forcibly insert a service wire into the terminals of the connector when connecting.
(d) Measure the resistance according to the value(s) in the table below.
Resistance:
NG -- CHECK FLOOR WIRE (OPEN)
OK -- Continue to next step.
5. CHECK OCCUPANT CLASSIFICATION ECU CIRCUIT (SHORT)
(a) Disconnect the service wire from connector "B".
(b) Measure the resistance according to the value(s) in the table below.
Resistance:
NG -- CHECK FLOOR WIRE (SHORT)
OK -- Continue to next step.
6. CHECK OCCUPANT CLASSIFICATION ECU CIRCUIT (SHORT TO GROUND)
(a) Measure the resistance according to the value(s) in the table below.
Resistance:
NG -- CHECK FLOOR WIRE (SHORT TO GROUND)
OK -- Continue to next step.
7. CHECK DTC
(a) Connect the connectors to the occupant classification ECU and the center airbag sensor assembly.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the ignition switch to the ON position.
(d) 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.
(e) Turn the ignition switch to the LOCK position.
(f) Turn the ignition switch to the ON position.
(g) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1790 is not output.
HINT: Codes other than DTC B1790 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.
8. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the negative (-) terminal cable from the battery.
(c) Replace the occupant classification ECU Removal.
HINT: Perform the inspection using parts from a normal vehicle if possible.
NEXT -- Continue to next step.
9. PERFORM ZERO POINT CALIBRATION
(a) Connect the negative (-) terminal cable to the battery.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the Techstream, perform "Zero point calibration" Programming and Relearning.
OK:
"Zero Point Calibration is Complete." is displayed.
NEXT -- Continue to next step.
10. PERFORM SENSITIVITY CHECK
(a) Using the Techstream, perform "Sensitivity check" Programming and Relearning.
Standard value:
27 to 33 kg (59.52 to 72.75 lb)
NEXT -- Continue to next step.
11. 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.
(d) Turn the ignition switch to the ON position.
(e) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1790 is not output.
HINT: Codes 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 -- END
12. CHECK FLOOR WIRE (SHORT TO B+)
(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 floor wire connector from the seat wire No. 1.
(d) Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
(e) Turn the ignition switch to the ON position.
(f) Measure the voltage according to the value(s) in the table below.
Voltage:
NG -- REPAIR OR REPLACE FLOOR WIRE
OK -- REPAIR OR REPLACE SEAT WIRE NO. 1
13. CHECK FLOOR WIRE (OPEN)
(a) Disconnect the floor wire connector from the seat wire No. 1.
HINT: The service wire has already been inserted into the connector "B".
(b) Measure the resistance according to the value(s) in the table below.
Resistance:
NG -- REPAIR OR REPLACE FLOOR WIRE
OK -- REPAIR OR REPLACE SEAT WIRE NO. 1
14. CHECK FLOOR WIRE (SHORT)
(a) Disconnect the floor wire connector from the seat wire No. 1.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:
NG -- REPAIR OR REPLACE FLOOR WIRE
OK -- REPAIR OR REPLACE SEAT WIRE NO. 1
15. CHECK FLOOR WIRE (SHORT TO GROUND)
(a) Disconnect the floor wire connector from the seat wire No. 1.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:
NG -- REPAIR OR REPLACE FLOOR WIRE
OK -- REPAIR OR REPLACE SEAT WIRE NO. 1