Toyota Tundra Service Manual: 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.

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.

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

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PROCEDURE

(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

(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

(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:

(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:

(h) Disconnect the service wire from connector B.

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

Standard Resistance:

NG

GO TO STEP 7

OK

(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.

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(e) Turn the ignition switch off.

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

(g) Check for DTCs.

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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

(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.

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HINT:

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

NEXT

(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.

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(d) Turn the ignition switch off.

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

(f) Check for DTCs.

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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

(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:

(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:

(i) Disconnect the service wire from connector B.

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

Standard Resistance:

OK

REPLACE FRONT SEAT INNER BELT ASSEMBLY LH

NG

REPLACE FLOOR WIRE