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B1790





SUPPLEMENTAL RESTRAINT SYSTEM: 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 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

NOTICE:
* w/ Navigation System (for HDD):
After the power switch is turned off, the display and navigation module display (HDD navigation system) records various types of memory and settings. As a result, after turning the power switch off, be sure to wait for the time specified in the following table before disconnecting the cable from the negative (-) battery terminal.

Waiting Time before Disconnecting Cable from Negative (-) Battery Terminal:





* 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 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.

PROCEDURE

1. CHECK FOR DTC

(a) Turn the power switch ON (IG).

(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 power switch OFF.

(e) Turn the power switch ON (IG).

(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 Diagnosis System

2. CHECK CONNECTION OF CONNECTOR

(a) Turn the power switch OFF.

(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.

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 power switch ON (IG).

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

Standard voltage:





(d) Turn the power switch OFF.

(e) Disconnect the negative (-) terminal cable from the battery.

(f) Using a service wire, connect terminals 16 (FSR+) and 22 (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 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 power switch ON (IG).

(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 power switch OFF.

(h) Turn the power switch ON (IG).

(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 -- REPLACE FRONT SEAT SET (OCCUPANT CLASSIFICATION ECU)

OK -- USE SIMULATION METHOD TO CHECK Diagnosis System

6. REPLACE FRONT SEAT SET (OCCUPANT CLASSIFICATION ECU)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch ON (IG).

(c) Using the Techstream, save the ECU data from the ECU which was installed on the vehicle Registration.

(d) Turn the power switch OFF.

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

(f) Replace the front seat set (occupant classification ECU) Disassembly.

(g) Connect the negative (-) terminal cable to the battery.

(h) Turn the power switch ON (IG).

(i) Using the Techstream, load the previous ECU data stored in the Techstream into the new ECU Registration.

(j) Turn the power switch OFF.

(k) Turn the power switch ON (IG).

(l) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.

HINT
If the DTCs are not cleared at this time, past DTCs will remain.

NEXT -- Continue to next step.

7. CHECK FOR DTC

(a) Turn the power switch ON (IG).

(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 power switch OFF.

(e) Turn the power switch ON (IG).

(f) 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 -- REPLACE CENTER AIRBAG SENSOR ASSEMBLY
OK -- Continue to next step.

8. PERFORM SENSITIVITY CHECK

(a) Perform the sensitivity check Initialization.

NEXT -- END

9. REPLACE CENTER AIRBAG SENSOR ASSEMBLY

(a) Turn the power switch OFF.

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

(c) Replace the center airbag sensor Removal.

NEXT -- Continue to next step.

10. PERFORM SENSITIVITY CHECK

(a) Perform the sensitivity check Initialization.

NEXT -- END

11. CHECK FLOOR WIRE

(a) Turn the power switch OFF.





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

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

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

(e) Turn the power switch ON (IG).

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

Standard voltage:





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

(h) Disconnect the negative (-) terminal cable from the battery.

(i) Using service wire, connect terminals 16 (FSR+) and 22 (FSR-) of connector B.

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

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

Standard resistance:





(k) Disconnect the service wire from connector B.

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

Standard resistance:





NG -- REPLACE FLOOR WIRE

OK -- REPLACE FRONT SEAT WIRE RH
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