Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

Vehicle Interior. Corolla. Zre142 Aze141
Supplemental Restraint Systems. Corolla. Zre142 Aze141

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK CONNECTORS

CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT TO B+)

CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (OPEN)

CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT)

CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT TO GROUND)

RECHECK FOR DTC

REPLACE OCCUPANT CLASSIFICATION ECU

RECHECK FOR DTC

PERFORM SENSITIVITY CHECK

REPLACE CENTER AIRBAG SENSOR ASSEMBLY

PERFORM SENSITIVITY CHECK

CHECK NO. 2 FLOOR WIRE (SHORT TO B+)

CHECK NO. 2 FLOOR WIRE (OPEN)

CHECK NO. 2 FLOOR WIRE (SHORT)

CHECK NO. 2 FLOOR WIRE (SHORT TO GROUND)

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.

DTC No.
DTC Detecting Condition
Trouble Area
B1790
  1. The occupant classification ECU receives a short circuit signal, an open circuit signal and short circuit to ground signal or a short circuit to B+ signal in the center airbag sensor assembly communication circuit for 2 seconds.
  2. Center airbag sensor assembly malfunction
  3. Occupant classification ECU malfunction
  1. No. 2 floor wire
  2. Front seat wire RH
  3. Occupant classification ECU
  4. Center airbag sensor assembly
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


Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction


INSPECTION PROCEDURE

HINT:
  1. If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to access the underside of the seat cushion.
  2. In the above case, hold the seat so that it does not fall down. Holding the seat for a long period of time may damage the seat or deform the seat rails. Hold the seat only as necessary.
1.CHECK CONNECTORS

  1. Turn the ignition switch off.

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

  1. Check that the connectors are properly connected to the occupant classification ECU and the center airbag sensor assembly.

    OK:
    The connectors are properly connected.
    HINT:
    If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

  1. Disconnect the connectors from the center airbag sensor assembly and the occupant classification ECU.

  1. Check that the terminals of the connectors are not damaged.

    OK:
    The terminals are not deformed or damaged.


NG
REPLACE WIRE HARNESS
OK


2.CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT TO B+)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

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

  1. Turn the ignition switch to ON.

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    R2-11 (FSR+) - Body ground
    		Ignition switch ON
    		Below 1 V
    R2-12 (FSR-) - Body ground
    		Ignition switch ON
    		Below 1 V


NG
Go to step 12
OK


3.CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (OPEN)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Turn the ignition switch off.

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

  1. Using SST, connect terminals 12 (FSR+) and 13 (FSR-) of connector B.

    NOTICE:
    Do not forcibly insert SST into the terminals of the connector when connecting the wire.
SST
09843-18040

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    R2-11 (FSR+) - R2-12 (FSR-)
    		Always
    		Below 1 Ω


NG
Go to step 13
OK


4.CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Disconnect SST from connector B.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    R2-11 (FSR+) - R2-12 (FSR-)
    		Always
    		1 MΩ or higher


NG
Go to step 14
OK


5.CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT TO GROUND)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    R2-11 (FSR+) - Body ground
    		Always
    		1 MΩ or higher
    R2-12 (FSR-) - Body ground
    		Always
    		1 MΩ or higher


NG
Go to step 15
OK


6.RECHECK FOR DTC

  1. Connect the connectors to the occupant classification ECU and the center airbag sensor assembly.

  1. Connect the Techstream to the DLC3.

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

  1. Turn the ignition switch to ON.

  1. Clear the DTCs stored in the occupant classification ECU (COROLLA_ZRE142 RM0000010VK07TX.html).

  1. Clear the DTCs stored in the center airbag sensor assembly (COROLLA_ZRE142 RM000000XFE0H1X.html).

  1. Turn the ignition switch off.

  1. Turn the ignition switch to ON.

  1. Using the Techstream, check for occupant classification ECU DTCs (COROLLA_ZRE142 RM0000010VK07TX.html).

    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
Go to step 7
OK

USE SIMULATION METHOD TO CHECK (COROLLA_ZRE142 RM0000010VJ07XX.html)

7.REPLACE OCCUPANT CLASSIFICATION ECU

  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to ON.

  1. Using the Techstream, save the ECU data from the ECU currently installed on the vehicle (COROLLA_ZRE142 RM000001QX402OX.html).

  1. Turn the ignition switch off.

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

  1. Replace the occupant classification ECU (COROLLA_ZRE142 RM0000011JG03CX.html).

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

  1. Turn the ignition switch to ON.

  1. Using the Techstream, load the previous ECU data stored into the new ECU (COROLLA_ZRE142 RM000001QX402OX.html).

  1. Turn the ignition switch off.

  1. Turn the ignition switch to ON.

  1. Clear the DTCs stored in the memory (COROLLA_ZRE142 RM0000010VK07TX.html).

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

NEXT


8.RECHECK FOR DTC

  1. Turn the ignition switch to ON.

  1. Clear the DTCs stored in the occupant classification ECU (COROLLA_ZRE142 RM0000010VK07TX.html).

  1. Clear the DTCs stored in the center airbag sensor assembly (COROLLA_ZRE142 RM000000XFE0H1X.html).

  1. Turn the ignition switch off.

  1. Turn the ignition switch to ON.

  1. Using the Techstream, check for occupant classification ECU DTCs (COROLLA_ZRE142 RM0000010VK07TX.html).

    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
Go to step 10
OK


9.PERFORM SENSITIVITY CHECK

  1. Perform the sensitivity check (COROLLA_ZRE142 RM0000010VN07SX.html).


NEXT

END

10.REPLACE CENTER AIRBAG SENSOR ASSEMBLY

  1. Turn the ignition switch off.

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

  1. Replace the center airbag sensor assembly (COROLLA_ZRE142 RM000000UWV074X.html).


NEXT


11.PERFORM SENSITIVITY CHECK

  1. Perform the sensitivity check (COROLLA_ZRE142 RM0000010VN07SX.html).


NEXT

END

12.CHECK NO. 2 FLOOR WIRE (SHORT TO B+)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Turn the ignition switch off.

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

  1. Disconnect the front seat wire RH connector from the No. 2 floor wire.

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

  1. Turn the ignition switch to ON.

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    MR1-5 (FSR+) - Body ground
    		Ignition switch ON
    		Below 1 V
    MR1-10 (FSR-) - Body ground
    		Ignition switch ON
    		Below 1 V


NG
REPLACE NO. 2 FLOOR WIRE
OK

REPLACE FRONT SEAT WIRE RH

13.CHECK NO. 2 FLOOR WIRE (OPEN)


  1. Disconnect the front seat wire RH connector from the No. 2 floor wire.


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

    HINT:
    SST has already been inserted into connector B.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    MR1-5 (FSR+) - MR1-10 (FSR-)
    		Always
    		Below 1 Ω


NG
REPLACE NO. 2 FLOOR WIRE
OK

REPLACE FRONT SEAT WIRE RH

14.CHECK NO. 2 FLOOR WIRE (SHORT)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Disconnect the front seat wire RH connector from the No. 2 floor wire.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    MR1-5 (FSR+) - MR1-10 (FSR-)
    		Always
    		1 MΩ or higher


NG
REPLACE NO. 2 FLOOR WIRE
OK

REPLACE FRONT SEAT WIRE RH

15.CHECK NO. 2 FLOOR WIRE (SHORT TO GROUND)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1790 Center Airbag Sensor Assembly Communication Circuit Malfunction

  1. Disconnect the front seat wire RH connector from the No. 2 floor wire.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    MR1-5 (FSR+) - Body ground
    		Always
    		1 MΩ or higher
    MR1-10 (FSR-) - Body ground
    		Always
    		1 MΩ or higher


NG
REPLACE NO. 2 FLOOR WIRE
OK

REPLACE FRONT SEAT WIRE RH