B1790

SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1790: Center Airbag Sensor Assembly Communication Circuit Malfunction
B1790 - Center Airbag Sensor Assembly Communication Circuit Malfunction

DESCRIPTION

The center airbag sensor assembly communication circuit consists of the occupant classification ECU and center airbag sensor assembly.

DTC B1790 is recorded when a malfunction is detected in the center airbag sensor assembly communication circuit.





WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see the under surface of 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 CONNECTORS

(a) Turn the ignition switch off.

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

(c) for Power seat:

Check that the connectors are properly connected to the center airbag sensor assembly and occupant classification ECU. Also check that the connectors that link the front seat wire RH and No. 2 floor wire are properly connected.

(d) for Manual seat:

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

OK:

The connectors are properly connected.

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

(e) for Power seat:

Disconnect the connectors from the center airbag sensor assembly and occupant classification ECU. Also disconnect the connectors that link the front seat wire RH and No. 2 floor wire.

(f) for Manual seat:

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

(g) Check that the connector terminals are not damaged.

OK:

The terminals are not deformed or damaged.

Result

Result:

C -- REPLACE NO. 2 FLOOR WIRE

B -- REPLACE WIRE HARNESS
A -- Continue to next step.

2. CHECK VEHICLE CONDITION

(a) Check the passenger seat type.

Result:

A
for Manual seat

B
for Power seat

B -- CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT TO B+)
A -- Continue to next step.

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

(a) Disconnect the connector from the center airbag sensor assembly and occupant classification ECU.





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

(c) Turn the ignition switch to ON.

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

Standard Voltage:





Text in Illustration

Text in Illustration:

NG -- REPLACE NO. 2 FLOOR WIRE
OK -- Continue to next step.

4. CHECK NO. 2 FLOOR WIRE (OPEN)

(a) Turn the ignition switch off.





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

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

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

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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE NO. 2 FLOOR WIRE
OK -- Continue to next step.

5. CHECK NO. 2 FLOOR WIRE (SHORT)

(a) Disconnect SST from connector B.





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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE NO. 2 FLOOR WIRE
OK -- Continue to next step.

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

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





Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE NO. 2 FLOOR WIRE
OK -- Continue to next step.

7. RECHECK DTC

(a) Connect the connectors to the occupant classification ECU and center airbag sensor assembly.

(b) Connect the Techstream to the DLC3.

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

(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 assembly DTC Check / Clear.

(g) Turn the ignition switch off.

(h) Turn the ignition switch to ON.

(i) Using the Techstream, check 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.

OK -- REPLACE OCCUPANT CLASSIFICATION ECU

OK -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

8. REPLACE OCCUPANT CLASSIFICATION ECU

(a) Turn the ignition switch off.

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

(c) Replace the occupant classification ECU Removal.

HINT
Perform the inspection using parts from a normal vehicle if possible.

NEXT -- Continue to next step.

9. PERFORM ZERO POINT CALIBRATION

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

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Using the Techstream, perform Zero Point Calibration Programming and Relearning.

OK:

"Zero Point Calibration is complete." is displayed.

NEXT -- Continue to next step.

10. PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check Programming and Relearning.

Standard:

27 to 33 kg (59.52 to 72.8 lb)

NEXT -- Continue to next step.

11. RECHECK 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 assembly DTC Check / Clear.

(d) Turn the ignition switch off.

(e) Turn the ignition switch to ON.

(f) Using the Techstream, check 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 Removal

OK -- END

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

(a) Connect the connectors that link the front seat wire RH and No. 2 floor wire.





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

(c) Turn the ignition switch to ON.

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

Standard Voltage:





Text in Illustration

Text in Illustration:

NG -- CHECK NO. 2 FLOOR WIRE (SHORT TO B+)
OK -- Continue to next step.

13. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (OPEN)

(a) Turn the ignition switch off.





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

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

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

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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- CHECK NO. 2 FLOOR WIRE (OPEN)
OK -- Continue to next step.

14. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT)

(a) Disconnect SST from connector B.





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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- CHECK FRONT SEAT WIRE RH (OPEN)
OK -- Continue to next step.

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

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





Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- CHECK NO. 2 FLOOR WIRE (SHORT)
OK -- Continue to next step.

16. RECHECK DTC

(a) Connect the connectors to the occupant classification ECU and center airbag sensor assembly.

(b) Connect the Techstream to the DLC3.

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

(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 assembly DTC Check / Clear.

(g) Turn the ignition switch off.

(h) Turn the ignition switch to ON.

(i) Using the Techstream, check 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 OCCUPANT CLASSIFICATION ECU

OK -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

17. REPLACE OCCUPANT CLASSIFICATION ECU

(a) Turn the ignition switch off.

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

(c) Replace the occupant classification ECU Removal.

HINT
Perform the inspection using parts from a normal vehicle if possible.

NEXT -- Continue to next step.

18. PERFORM ZERO POINT CALIBRATION

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

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Using the Techstream, perform Zero Point Calibration Programming and Relearning.

OK:

"Zero Point Calibration is complete." is displayed.

NEXT -- Continue to next step.

19. PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check Programming and Relearning.

Standard:

27 to 33 kg (59.5 to 72.8 lb)

NEXT -- Continue to next step.

20. RECHECK 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 assembly DTC Check / Clear.

(d) Turn the ignition switch off.

(e) Turn the ignition switch to ON.

(f) Using the Techstream, check 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 Removal

OK -- END

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

(a) Turn the ignition switch off.





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

(c) Disconnect the junction connector from the No. 2 floor wire.

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

(e) Turn the ignition switch to ON.

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

Standard Voltage:





Text in Illustration

Text in Illustration:

NG -- REPLACE NO. 2 FLOOR WIRE
OK -- Continue to next step.

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

(a) Turn the ignition switch off.





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

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

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

(e) Turn the ignition switch to ON.

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

Standard Voltage:





Text in Illustration

Text in Illustration:

NG -- REPLACE FRONT SEAT WIRE RH

OK -- REPLACE JUNCTION CONNECTOR

23. CHECK NO. 2 FLOOR WIRE (OPEN)

(a) Disconnect the junction connector from the No. 2 floor wire.





HINT
SST has already been inserted into connector B.

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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE NO. 2 FLOOR WIRE
OK -- Continue to next step.

24. CHECK FRONT SEAT WIRE RH (OPEN)

(a) Disconnect the front seat wire RH connector from the junction connector.





(b) Using SST, connect terminals 8 (FSR+) and 4 (FSR-) of connector E.

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

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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE FRONT SEAT WIRE RH

OK -- REPLACE JUNCTION CONNECTOR

25. CHECK NO. 2 FLOOR WIRE (SHORT)

(a) Disconnect the junction connector from the No. 2 floor wire.





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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE NO. 2 FLOOR WIRE
OK -- Continue to next step.

26. CHECK FRONT SEAT WIRE RH (SHORT)

(a) Disconnect the front seat wire RH connector from the junction connector.





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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE FRONT SEAT WIRE RH

OK -- REPLACE JUNCTION CONNECTOR

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

(a) Disconnect the junction connector from the No. 2 floor wire.





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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE NO. 2 FLOOR WIRE
OK -- Continue to next step.

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

(a) Disconnect the front seat wire RH connector from the junction connector.





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

Standard Resistance:





Text in Illustration

Text in Illustration:

NG -- REPLACE FRONT SEAT WIRE RH

OK -- REPLACE JUNCTION CONNECTOR