Toyota Tundra Service Manual: Seat Position Airbag Sensor Circuit Malfunction (B1653)

Toyota Tundra Service Manual / Vehicle Interior / Supplemental Restraint Systems / Airbag System / Seat Position Airbag Sensor Circuit Malfunction (B1653)

DESCRIPTION

The seat position airbag sensor circuit consists of the airbag sensor assembly and seat position airbag sensor.

DTC B1653 is stored when a malfunction is detected in the seat position airbag sensor circuit.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Test Mode / Check Mode

B1653

Seat Position Airbag Sensor Circuit Malfunction
  • The airbag sensor assembly detects a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the seat position airbag sensor circuit for 2 seconds.
  • A seat position airbag sensor malfunction.
  • An airbag sensor assembly malfunction
  • Floor wire
  • Front seat inner belt assembly LH
  • Seat position airbag sensor
  • Airbag sensor assembly

Comes on

Not applicable

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

    Click here

  • When disconnecting the cable from the negative (-) battery terminal while performing repairs, some systems need to be initialized after the cable is reconnected.

    Click here

PROCEDURE

1.

CHECK CONNECTION OF CONNECTORS

(a) Turn the ignition switch off.

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

(c) Check that the connectors are properly connected to the airbag sensor assembly and seat position airbag sensor.

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY
OK

2.

CHECK CONNECTORS

(a) Disconnect the connectors from the airbag sensor assembly and seat position airbag sensor.

*1

Seat Position Airbag Sensor

*2

Airbag Sensor Assembly

*3

Front Seat Inner Belt Assembly LH

*4

Floor Wire

(b) Check that the connectors (on the airbag sensor assembly side and seat position airbag sensor side) are not damaged.

OK:

Connectors are not deformed or damaged.

NG

REPLACE FLOOR WIRE OR FRONT SEAT INNER BELT ASSEMBLY LH
OK

3.

CHECK SEAT POSITION AIRBAG SENSOR CIRCUIT

(a) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

*1

Seat Position Airbag Sensor

*2

Airbag Sensor Assembly

*3

Front Seat Inner Belt Assembly LH

*4

Floor Wire

*5

Service Wire

*a

Front view of wire harness connector

(to Seat Position Airbag Sensor)

*b

Front view of wire harness connector

(to Airbag Sensor Assembly)

(b) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

AA-1 (GND) - Body ground

Ignition switch ON

Below 1 V

AA-2 (VS) - Body ground

Ignition switch ON

Below 1 V

(d) Turn the ignition switch off.

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

(f) Using a service wire, connect terminals 26 (LSP-) and 25 (LSP+) of connector B.

NOTICE:

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

AA-1 (GND) - AA-2 (VS)

Always

Below 1 Ω

(h) Disconnect the service wire from connector B.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

AA-1 (GND) - AA-2 (VS)

Always

1 MΩ or higher

AA-1 (GND) - Body ground

Always

1 MΩ or higher

AA-2 (VS) - Body ground

Always

1 MΩ or higher
NG

GO TO STEP 7

OK

4.

CHECK DTC

(a) Connect the connectors to the airbag sensor assembly and seat position airbag sensor.

*1

Seat Position Airbag Sensor

*2

Airbag Sensor Assembly

(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(c) Turn the ignition switch to ON, and wait for at least 60 seconds.

(d) Clear the DTCs.

Click here

(e) Turn the ignition switch off.

(f) Turn the ignition switch to ON, and wait for at least 60 seconds.

(g) Check for DTCs.

Click here

Result

Proceed to

DTC B1653 is not output

A

DTC B1653 is output

B

HINT:

Codes other than DTC B1653 may be output at this time, but they are not related to this check.

A

USE SIMULATION METHOD TO CHECK

B

5.

REPLACE SEAT POSITION AIRBAG SENSOR

(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 seat position airbag sensor.

Click here

HINT:

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

NEXT

6.

CHECK DTC

(a) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

*1

Seat Position Airbag Sensor

*2

Airbag Sensor Assembly

(b) Turn the ignition switch to ON, and wait for at least 60 seconds.

(c) Clear the DTCs.

Click here

(d) Turn the ignition switch off.

(e) Turn the ignition switch to ON, and wait for at least 60 seconds.

(f) Check for DTCs.

Click here

Result

Proceed to

DTC B1653 is not output

A

DTC B1653 is output

B

HINT:

Codes other than DTC B1653 may be output at this time, but they are not related to this check.

A

END (SEAT POSITION AIRBAG SENSOR WAS DEFECTIVE)
B

REPLACE AIRBAG SENSOR ASSEMBLY

7.

CHECK FLOOR WIRE

(a) Disconnect the floor wire connector from the front seat inner belt assembly LH.

*1

Seat Position Airbag Sensor

*2

Airbag Sensor Assembly

*3

Front Seat Inner Belt Assembly LH

*4

Floor Wire

*5

Service Wire

*a

Front view of wire harness connector

(to Front Seat Inner Belt Assembly LH)

*b

Front view of wire harness connector

(to Airbag Sensor Assembly)

(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(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

P7-3 (LSP+) - Body ground

Ignition switch ON

Below 1 V

P7-4 (LSP-) - Body ground

Ignition switch ON

Below 1 V

(e) Turn the ignition switch off.

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

(g) Using a service wire, connect terminals 26 (LSP-) and 25 (LSP+) of connector B.

NOTICE:

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

P7-3 (LSP+) - P7-4 (LSP-)

Always

Below 1 Ω

(i) Disconnect the service wire from connector B.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

P7-3 (LSP+) - P7-4 (LSP-)

Always

1 MΩ or higher

P7-3 (LSP+) - Body ground

Always

1 MΩ or higher

P7-4 (LSP-) - Body ground

Always

1 MΩ or higher
OK

REPLACE FRONT SEAT INNER BELT ASSEMBLY LH

NG

REPLACE FLOOR WIRE
    Occupant Classification System Malfunction (B1650)

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