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.





HINT: When DTC B1650/32 is detected as a result of troubleshooting for the AIRBAG SYSTEM, check the DTCs stored in the occupant classification ECU. When DTC B1790 is output, perform troubleshooting for the DTC.

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 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 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 -- CHECK CONNECTION OF CONNECTORS
OK -- USE SIMULATION METHOD TO CHECK
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 connected.
NG -- CONNECT CONNECTORS PROPERLY, THEN GO TO STEP 1
OK -- Continue to next step.
3. CHECK FLOOR WIRE NO. 2 (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.
Standard voltage:






NG -- REPLACE FLOOR WIRE NO. 2
OK -- Continue to next step.
4. CHECK FLOOR WIRE NO. 2 (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 terminals 16 (FSP+) and 24 (FSP-) 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.
Standard resistance:






NG -- REPLACE FLOOR WIRE NO. 2
OK -- Continue to next step.
5. CHECK FLOOR WIRE NO. 2 (SHORT)





(a) Disconnect the service wire from connector B.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE FLOOR WIRE NO. 2
OK -- Continue to next step.
6. CHECK FLOOR WIRE NO. 2 (SHORT TO GROUND)





(a) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE FLOOR WIRE NO. 2
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 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.

NG -- REPLACE OCCUPANT CLASSIFICATION ECU
OK -- USE SIMULATION METHOD TO CHECK
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 intelligent tester to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the intelligent tester, perform "zero point calibration" Programming and Relearning.
OK:
"COMPLETED" is displayed.
NEXT -- Continue to next step.
10. PERFORM SENSITIVITY CHECK
(a) Using the intelligent tester, 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 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