Toyota Venza manuals

Toyota Venza: Center Airbag Sensor Assembly Communication Circuit Malfunction (B1790)

Toyota Venza Service Manual / Supplemental Restraint Systems / Occupant Classification System / Center Airbag Sensor Assembly Communication Circuit Malfunction (B1790)

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.

DTC No.

DTC Detecting Condition

Trouble Area

B1790

  • The occupant classification ECU receives a line short circuit signal, an open circuit signal, a short circuit to ground signal or a short circuit to B+ signal in the center airbag sensor assembly communication circuit.
  • Occupant classification ECU malfunction
  • Center airbag sensor assembly malfunction
  • Occupant classification ECU
  • Center airbag sensor assembly
  • Front seat wire RH (for Power seat)
  • Floor wire No. 2
  • Junction connector

WIRING DIAGRAM


CAUTION / NOTICE / HINT

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

Proceed to

OK

A

NG (for Power seat)

B

NG (for Manual seat)

C


B

REPLACE WIRE HARNESS


C

REPLACE NO. 2 FLOOR WIRE


A

2.

CHECK VEHICLE CONDITION

(a) Check the passenger seat type.

A

for Manual seat

B

for Power seat


B

GO TO STEP 12


A

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:

Tester Connection

Switch Condition

Specified Condition

M14-8 (FSR+) - Body ground

Ignition switch ON

Below 1 V

M14-4 (FSR-) - Body ground

Ignition switch ON

Below 1 V

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

No. 2 Floor Wire

*4

Front view of wire harness connector

(to Occupant Classification ECU)

*5

Connector C


NG

REPLACE NO. 2 FLOOR WIRE


OK

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 16 (FSR+) and 24 (FSR-) 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:

Tester Connection

Condition

Specified Condition

M14-8 (FSR+) - M14-4 (FSR-)

Always

Below 1 Ω

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

No. 2 Floor Wire

*4

Front view of wire harness connector

(to Center Airbag Sensor Assembly)

*5

Front view of wire harness connector

(to Occupant Classification ECU)

*6

Connector B

*7

Connector C

-

-


NG

REPLACE NO. 2 FLOOR WIRE


OK

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:

Tester Connection

Condition

Specified Condition

M14-8 (FSR+) - M14-4 (FSR-)

Always

1 MΩ or higher

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

No. 2 Floor Wire

*4

Front view of wire harness connector

(to Occupant Classification ECU)

*5

Connector C


NG

REPLACE NO. 2 FLOOR WIRE


OK

6.

CHECK NO. 2 FLOOR WIRE (SHORT TO GROUND)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

M14-8 (FSR+) - Body ground

Always

1 MΩ or higher

M14-4 (FSR-) - Body ground

Always

1 MΩ or higher

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

No. 2 Floor Wire

*4

Front view of wire harness connector

(to Occupant Classification ECU)

*5

Connector C



NG

REPLACE NO. 2 FLOOR WIRE


OK

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 (See page ).


(f) Clear the DTCs stored in the center airbag sensor assembly (See page ).


(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 (See page ).


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

USE SIMULATION METHOD TO CHECK


OK

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 (See page ).


HINT:

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


NEXT

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 (See page ).


OK:

"Zero Point Calibration is complete." is displayed.


NEXT

10.

PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check (See page ).


Standard:

27 to 33 kg (59.52 to 72.8 lb)


NEXT

11.

RECHECK DTC

(a) Turn the ignition switch to ON.

(b) Clear the DTCs stored in the occupant classification ECU (See page ).


(c) Clear the DTCs stored in the center airbag sensor assembly (See page ).


(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 (See page ).


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

END


NG

REPLACE CENTER AIRBAG SENSOR ASSEMBLY

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:

Tester Connection

Switch Condition

Specified Condition

S12-8 (FSR+) - Body ground

Ignition switch ON

Below 1 V

S12-4 (FSR-) - Body ground

Ignition switch ON

Below 1 V

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Junction Connector

*4

Front view of wire harness connector

(to Occupant Classification ECU)

*5

Connector E


NG

GO TO STEP 21


OK

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 16 (FSR+) and 24 (FSR-) 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:

Tester Connection

Condition

Specified Condition

S12-8 (FSR+) - S12-4 (FSR-)

Always

Below 1 Ω

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Junction Connector

*4

Front view of wire harness connector

(to Center Airbag Sensor Assembly)

*5

Front view of wire harness connector

(to Occupant Classification ECU)

*6

Connector B

*7

Connector E

-

-


NG

GO TO STEP 23


OK

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:

Tester Connection

Condition

Specified Condition

S12-8 (FSR+) - S12-4 (FSR-)

Always

1 MΩ or higher

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Junction Connector

*4

Front view of wire harness connector

(to Occupant Classification ECU)

*5

Connector E


NG

GO TO STEP 25


OK

15.

CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT TO GROUND)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

S12-8 (FSR+) - Body ground

Always

1 MΩ or higher

S12-4 (FSR-) - Body ground

Always

1 MΩ or higher

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Junction Connector

*4

Front view of wire harness connector

(to Occupant Classification ECU)

*5

Connector E



NG

GO TO STEP 27


OK

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 (See page ).


(f) Clear the DTCs stored in the center airbag sensor assembly (See page ).


(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 (See page ).


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

USE SIMULATION METHOD TO CHECK


NG

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 (See page ).


HINT:

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


NEXT

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 (See page ).


OK:

"Zero Point Calibration is complete." is displayed.


NEXT

19.

PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check (See page ).


Standard:

27 to 33 kg (59.5 to 72.8 lb)


NEXT

20.

RECHECK DTC

(a) Turn the ignition switch to ON.

(b) Clear the DTCs stored in the occupant classification ECU (See page ).


(c) Clear the DTCs stored in the center airbag sensor assembly (See page ).


(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 (See page ).


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

END


NG

REPLACE CENTER AIRBAG SENSOR ASSEMBLY

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:

Tester Connection

Switch Condition

Specified Condition

M26-13 (FSR+) - Body ground

Ignition switch ON

Below 1 V

M26-14 (FSR-) - Body ground

Ignition switch ON

Below 1 V

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Front Seat Wire RH

*4

Junction Connector

*5

No. 2 Floor Wire

*6

Front view of wire harness connector

(to Junction Connector)

*7

Connector C


NG

REPLACE NO. 2 FLOOR WIRE


OK

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:

Tester Connection

Switch Condition

Specified Condition

S14-14 (FSR+) - Body ground

Ignition switch ON

Below 1 V

S14-13 (FSR-) - Body ground

Ignition switch ON

Below 1 V

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Front Seat Wire RH

*4

Junction Connector

*5

No. 2 Floor Wire

*6

Front view of wire harness connector

(to Junction Connector)

*7

Connector D


OK

REPLACE JUNCTION CONNECTOR


NG

REPLACE FRONT SEAT WIRE RH

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:

Tester Connection

Condition

Specified Condition

M26-13 (FSR+) - M26-14 (FSR-)

Always

Below 1 Ω

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Front Seat Wire RH

*4

Junction Connector

*5

No. 2 Floor Wire

*6

Front view of wire harness connector

(to Center Airbag Sensor Assembly)

*7

Front view of wire harness connector

(to Junction Connector)

*8

Connector B

*9

Connector C

-

-


NG

REPLACE NO. 2 FLOOR WIRE


OK

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:

Tester Connection

Condition

Specified Condition

S14-14 (FSR+) - S14-13 (FSR-)

Always

Below 1 Ω

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Front Seat Wire RH

*4

Junction Connector

*5

No. 2 Floor Wire

*6

Front view of wire harness connector

(to Junction Connector)

*7

Front view of wire harness connector

(to Occupant Classification ECU)

*8

Connector D

*9

Connector E

-

-


OK

REPLACE JUNCTION CONNECTOR


NG

REPLACE FRONT SEAT WIRE RH

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:

Tester Connection

Condition

Specified Condition

M26-13 (FSR+) - M26-14 (FSR-)

Always

1 MΩ or higher

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Front Seat Wire RH

*4

Junction Connector

*5

No. 2 Floor Wire

*6

Front view of wire harness connector

(to Junction Connector)

*7

Connector C


NG

REPLACE NO. 2 FLOOR WIRE


OK

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:

Tester Connection

Condition

Specified Condition

S14-14 (FSR+) - S14-13 (FSR-)

Always

1 MΩ or higher

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Front Seat Wire RH

*4

Junction Connector

*5

No. 2 Floor Wire

*6

Front view of wire harness connector

(to Junction Connector)

*7

Connector D


OK

REPLACE JUNCTION CONNECTOR


NG

REPLACE FRONT SEAT WIRE RH

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:

Tester Connection

Condition

Specified Condition

M26-13 (FSR+) - Body ground

Always

1 MΩ or higher

M26-14 (FSR-) - Body ground

Always

1 MΩ or higher

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Front Seat Wire RH

*4

Junction Connector

*5

No. 2 Floor Wire

*6

Front view of wire harness connector

(to Junction Connector)

*7

Connector C


NG

REPLACE NO. 2 FLOOR WIRE


OK

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:

Tester Connection

Condition

Specified Condition

S14-14 (FSR+) - Body ground

Always

1 MΩ or higher

S14-13 (FSR-) - Body ground

Always

1 MΩ or higher

Text in Illustration

*1

Occupant Classification ECU

*2

Center Airbag Sensor Assembly

*3

Front Seat Wire RH

*4

Junction Connector

*5

No. 2 Floor Wire

*6

Front view of wire harness connector

(to Junction Connector)

*7

Connector D


OK

REPLACE JUNCTION CONNECTOR


NG

REPLACE FRONT SEAT WIRE RH

Open in Occupant Classification ECU Battery Positive Line (B1794)
DESCRIPTION This circuit consists of the occupant classification ECU and power source circuit (battery, fuse and wire harness). DTC B1794 is recorded when a malfunction is detected in the occupant ...

Rear Occupant Classification Sensor LH Collision Detection (B1787)
DESCRIPTION DTC B1787 is output when the occupant classification ECU receives a collision detection signal sent by the rear occupant classification sensor LH if an accident occurs. DTC B1787 is ...

Other materials about Toyota Venza:

Lost Communication with ECM / PCM (U0100)
DESCRIPTION DTC No. DTC Detection Condition Trouble Area U0100 No communication from the ECM continues. ECM main wire or connector Power source circuit of ECM ECM ...

Installation
INSTALLATION CAUTION / NOTICE / HINT HINT: Use the same procedure for the RH side and LH side. The procedure listed below is for the LH side. PROCEDURE 1. INSTALL REAR AXLE CARRIER SUB-ASSEMBLY (a) Temporarily install the rea ...

On-vehicle Inspection
ON-VEHICLE INSPECTION CAUTION / NOTICE / HINT CAUTION: Be sure to follow the correct removal and installation procedures of the driver side knee airbag assembly. PROCEDURE 1. INSPECT DRIVER SIDE KNEE AIRBAG ASSEMBLY (VEHICLE NOT INVOLVED IN COLLISION) ...

© 2016-2019 Copyright www.tovenza.com

0.2445