Dtc B1772 Seat Position Sensor Circuit Malfunction

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

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK CONNECTORS

CHECK FRONT SEAT WIRE RH (SHORT TO B+)

CHECK FRONT SEAT WIRE RH (OPEN)

CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)

CHECK FRONT SEAT WIRE RH (SHORT)

CHECK FOR DTC

INSPECT SEAT POSITION AIRBAG SENSOR (PASSENGER SIDE)

REPLACE OCCUPANT CLASSIFICATION ECU

PERFORM SENSITIVITY CHECK

DTC B1772 Seat Position Sensor Circuit Malfunction


DESCRIPTION

The seat position sensor circuit consists of the occupant classification ECU and the seat position airbag sensor (passenger side).
The seat position airbag sensor sends the seat position signal to the occupant classification ECU to control the dual stage deployment of the front passenger airbag.
DTC B1772 is recorded when a malfunction is detected in the seat position sensor circuit.

DTC No.
DTC Detection Condition
Trouble Area
B1772
  1. Occupant classification ECU receives a short circuit signal, open circuit signal and short circuit to ground signal or short circuit to B+ signal in seat position sensor circuit for 2 seconds.
  2. Seat position airbag sensor (Passenger side) malfunction
  3. Occupant classification ECU malfunction
  1. Front seat wire RH
  2. Seat position airbag sensor (Passenger side)
  3. Occupant classification ECU
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, and perform troubleshooting for those DTCs first.

WIRING DIAGRAM


Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1772 Seat Position Sensor Circuit Malfunction


INSPECTION PROCEDURE

HINT:
  1. If troubleshooting (wire harness inspection) is difficult to perform, remove the 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 tip over. Holding the seat up for a long period of time may damage the seat or deform the seat rails. Hold the seat up only for as long as necessary.
1.CHECK CONNECTORS

  1. Turn the ignition switch off.

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

  1. Check that the connectors are properly connected to the occupant classification ECU and the seat position airbag sensor (passenger side).

    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 occupant classification ECU and the seat position airbag sensor (passenger side).

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

    OK:
    The terminals are not deformed or damaged.


NG
REPLACE FRONT SEAT WIRE RH
OK


2.CHECK FRONT SEAT WIRE RH (SHORT TO B+)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1772 Seat Position Sensor 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
    R2-4 (SP) - Body ground
    		Ignition switch ON
    		Below 1 V
    R2-3 (GSP) - Body ground
    		Ignition switch ON
    		Below 1 V


NG
REPLACE FRONT SEAT WIRE RH
OK


3.CHECK FRONT SEAT WIRE RH (OPEN)


  1. Turn the ignition switch off.


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1772 Seat Position Sensor Circuit Malfunction

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

  1. Using SST, connect terminals 2 (SP) and 1 (GSP) of connector C.

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

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    R2-4 (SP) - R2-3 (GSP)
    		Always
    		Below 1 Ω


NG
REPLACE FRONT SEAT WIRE RH
OK


4.CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1772 Seat Position Sensor Circuit Malfunction

  1. Disconnect SST from connector C.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    R2-4 (SP) - Body ground
    		Always
    		 1 MΩ or higher
    R2-3 (GSP) - Body ground
    		Always
    		 1 MΩ or higher


NG
REPLACE FRONT SEAT WIRE RH
OK


5.CHECK FRONT SEAT WIRE RH (SHORT)


    Corolla. Zre142 Aze141.Supplemental Restraint Systems.Airbag System. Dtc B1772 Seat Position Sensor Circuit Malfunction

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    R2-4 (SP) - R2-3 (GSP)
    		Always
    		 1 MΩ or higher


NG
REPLACE FRONT SEAT WIRE RH
OK


6.CHECK FOR DTC

  1. Connect the connectors to the occupant classification ECU and the seat position airbag sensor (passenger side).

  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. Check for DTCs (COROLLA_ZRE142 RM0000010VK07TX.html).

    OK:
    DTC B1772 is not output.
    HINT:
    DTCs other than B1772 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

7.INSPECT SEAT POSITION AIRBAG SENSOR (PASSENGER SIDE)

  1. Turn the ignition switch off.

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

  1. Replace the seat position airbag sensor with a known good part (passenger side) (COROLLA_ZRE142 RM000000UWJ066X.html).

    HINT:
    1. Perform an inspection using known good parts from another vehicle if possible.
    2. The seat position airbag sensor is installed on the driver side.

  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. Check for DTCs (COROLLA_ZRE142 RM0000010VK07TX.html).

    OK:
    DTC B1772 is not output.
    HINT:
    DTCs other than B1772 may be output at this time, but they are not related to this check.


NG
Go to step 8
OK

END

8.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


9.PERFORM SENSITIVITY CHECK

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


NEXT

END