B1772

SUPPLEMENTAL RESTRAINT SYSTEM: OCCUPANT CLASSIFICATION SYSTEM (for Bench Seat Type): B1772: Seat Position Sensor Circuit Malfunction
B1772 - Seat Position Sensor Circuit Malfunction

DESCRIPTION

The seat position sensor circuit consists of the occupant classification ECU and the seat position sensor.

The seat position sensor sends the seat position signal to the occupant classification ECU to control the dual stage deployment of the front passenger airbag assembly.

DTC B1772 is recorded when a malfunction is detected in the seat position sensor circuit.





HINT
* When DTC B1650/32 is detected as a result of troubleshooting the supplemental restraint system, check the DTCs stored in the occupant classification ECU, and perform troubleshooting for those DTCs first.
* Use the Techstream to check for DTCs of the occupant classification ECU, otherwise the DTC cannot be read.

WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
* If troubleshooting (wire harness inspection) is difficult to perform, remove the passenger seat installation bolts to see the under surface of the seat cushion.
* 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 cause problems, such as seat rail deformation. Hold the seat up only for as long as necessary.

PROCEDURE

1. CHECK DTC

(a) Turn the ignition switch to the ON position.

(b) Clear the DTCs stored in the memory Occupant Classification System (for Bench Seat Type).

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 Occupant Classification System (for Bench Seat Type).

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.

OK -- USE SIMULATION METHOD TO CHECK
NG -- Continue to next step.

2. CHECK CONNECTORS

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

OK:

The connectors are properly connected.

(d) Disconnect the connectors from the occupant classification ECU and the seat position sensor.

(e) Check that the terminals of the connectors are not damaged.

OK:

The terminals are not deformed or damaged.

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

NG -- REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
OK -- Continue to next step.

3. CHECK NO. 1 SEAT WIRE (TO B+)

(a) Disconnect the connectors from the occupant classification ECU and the seat position sensor.





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

(c) Turn the ignition switch to the ON position.

(d) Measure the voltage.

Standard voltage:





NG -- REPAIR OR REPLACE NO. 1 SEAT WIRE
OK -- Continue to next step.

4. CHECK NO. 1 SEAT WIRE (FOR 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 S28-2 (SP) and S28-1 (GSP) of connector C.

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

(d) Measure the resistance.

Standard resistance:





NG -- REPAIR OR REPLACE NO. 1 SEAT WIRE
OK -- Continue to next step.

5. CHECK NO. 1 SEAT WIRE (TO GROUND)

(a) Disconnect the service wire from connector C.





(b) Measure the resistance.

Standard resistance:





NG -- REPAIR OR REPLACE NO. 1 SEAT WIRE
OK -- Continue to next step.

6. CHECK NO. 1 SEAT WIRE (FOR SHORT)





(a) Measure the resistance.

Standard resistance:





NG -- REPAIR OR REPLACE NO. 1 SEAT WIRE
OK -- Continue to next step.

7. CHECK DTC

(a) Connect the connectors to the occupant classification ECU and the seat position sensor.

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

(c) Turn the ignition switch to the ON position.

(d) Clear the DTCs stored in the memory Occupant Classification System (for Bench Seat Type).

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 Occupant Classification System (for Bench Seat Type).

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.

OK -- USE SIMULATION METHOD TO CHECK
NG -- Continue to next step.

8. REPLACE SEAT POSITION SENSOR

(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) Replace the seat position sensor Initialization.

HINT
* Perform the inspection using parts from a normal vehicle if possible.
* The seat position sensor is installed on the driver side.

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

(e) Turn the ignition switch to the ON position.

(f) Clear the DTCs stored in the memory Occupant Classification System (for Bench Seat Type).

HINT
First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.

(g) Turn the ignition switch to the LOCK position.

(h) Turn the ignition switch to the ON position.

(i) Check the DTCs Occupant Classification System (for Bench Seat Type).

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.

OK -- END
NG -- Continue to next step.

9. REPLACE OCCUPANT CLASSIFICATION ECU

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to the ON position.

(c) Store the occupant classification ECU data into the Techstream Registration.

HINT
If the ECU data cannot be stored in the Techstream, replace the front seat cushion assembly (with occupant classification ECU and occupant classification sensor).

(d) Turn the ignition switch to the LOCK position.

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

(f) Replace the occupant classification ECU Removal.

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

(h) Turn the ignition switch to the ON position.

(i) Load the data from the previous ECU stored in the Techstream, into the newly installed ECU Registration.

(j) Turn the ignition switch to the LOCK position.

(k) Turn the ignition switch to the ON position.

(l) Clear the DTCs stored in the memory Occupant Classification System (for Bench Seat Type).

HINT
If DTC is not cleared at this time, past DTC will remain.

NEXT -- Continue to next step.

10. PERFORM SENSITIVITY CHECK

(a) Perform the sensitivity check Initialization.

NEXT -- END