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 communication circuit consists of the occupant classification ECU and the center airbag sensor.
DTC B1790 is recorded when a malfunction is detected in the center airbag sensor 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 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 a problem, such as seat rail deformation. Hold the seat only as necessary.
PROCEDURE
1. CHECK FOR DTC
(a) Turn the ignition switch to ON.
(b) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(c) Clear the DTCs stored in the center airbag sensor DTC Check / Clear.
(d) Turn the ignition switch to OFF.
(e) Turn the ignition switch to ON.
(f) Check for 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 CONNECTOR
OK -- USE SIMULATION METHOD TO CHECK
2. CHECK CONNECTION OF CONNECTOR
(a) Turn the ignition switch to OFF.
(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 and the center airbag sensor.
OK:
Connectors are properly connected.
NG -- CONNECT CONNECTORS PROPERLY
OK -- Continue to next step.
3. CHECK CONNECTOR
(a) Disconnect the connectors from the center airbag sensor and the occupant classification ECU.
(b) Check that the connectors (on the center airbag sensor side and occupant classification ECU 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
(a) Connect the negative (-) terminal cable to the battery.
(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 to OFF.
(e) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 second.
(f) 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 when connecting the wire.
(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 NO. 2 FLOOR WIRE
OK -- Continue to next step.
5. CHECK FOR DTC
(a) Connect the connectors to the occupant classification ECU and the center airbag sensor.
(b) Connect the Techstream to the DLC3.
(c) Connect the negative (-) terminal cable to the battery.
(d) Turn the ignition switch to ON.
(e) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(f) Clear the DTCs stored in the center airbag sensor DTC Check / Clear.
(g) Turn the ignition switch to OFF.
(h) Turn the ignition switch to ON.
(i) Using the Techstream, check for the DTCs of the occupant classification ECU 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 -- PERFORM REGISTRATION BEFORE ECU EXCHANGE
OK -- USE SIMULATION METHOD TO CHECK
6. PERFORM REGISTRATION BEFORE ECU EXCHANGE
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Using the Techstream, save the ECU data from the ECU which was installed on the vehicle Registration.
NEXT -- Continue to next step.
7. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Turn the ignition switch to OFF.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the occupant classification ECU Removal.
(d) Connect the negative (-) terminal cable to the battery.
NEXT -- Continue to next step.
8. PERFORM REGISTRATION AFTER ECU EXCHANGE
(a) Turn the ignition switch to ON.
(b) Using the Techstream, load the previous ECU data stored in the tester into the new ECU Registration.
NEXT -- Continue to next step.
9. PERFORM ZERO POINT CALIBRATION
(a) Using the Techstream, perform zero point calibration Initialization.
NEXT -- Continue to next step.
10. CHECK FOR DTC
HINT: Check that the zero point calibration is completed normally. If one of the following conditions is met, DTC B1797 will be output (refer to INITIALIZATION Initialization):
- Zero point calibration is performed when the conditions for the calibration are not satisfied.
- Zero point calibration has failed.
(a) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(b) Clear the DTCs stored in the center airbag sensor DTC Check / Clear.
(c) Turn the ignition switch to OFF.
(d) Turn the ignition switch to ON.
(e) Check for the DTCs of the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
Result:
C -- GO TO DTC B1797
B -- REPLACE CENTER AIRBAG SENSOR ASSEMBLY
A -- Continue to next step.
11. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END
12. REPLACE CENTER AIRBAG SENSOR ASSEMBLY
(a) Turn the ignition switch to OFF.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the center airbag sensor Removal.
(d) Connect the negative (-) terminal cable to the battery.
NEXT -- Continue to next step.
13. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END
14.
CHECK NO. 2 FLOOR WIRE
(a) Disconnect the front seat wire RH connector from the No. 2 floor wire.
(b) Connect the negative (-) terminal cable to the battery.
(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 to OFF.
(f) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(g) 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 when connecting the wire.
(h) Measure the resistance according to the value(s) in the table below.
Standard resistance:
(i) Disconnect the service wire from connector B.
(j) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPLACE NO. 2 FLOOR WIRE
OK -- REPLACE FRONT SEAT WIRE RH