Toyota Tundra Service Manual: Short in Side Squib (LH) Circuit (B1825-B1828)

Toyota Tundra Service Manual / Vehicle Interior / Supplemental Restraint Systems / Airbag System / Short in Side Squib (LH) Circuit (B1825-B1828)

DESCRIPTION

The front side squib LH circuit consists of the airbag sensor assembly and front seat airbag assembly LH.

The circuit instructs the SRS to deploy when deployment conditions are met.

These DTCs are stored when a malfunction is detected in the front side squib LH circuit.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Test Mode / Check Mode

B1825

Short in Side Squib (LH) Circuit

One of the following conditions is met:

  • The airbag sensor assembly detects a line short circuit signal 5 times in the front side squib LH circuit during the primary check.
  • A front seat airbag assembly LH malfunction.
  • An airbag sensor assembly malfunction.
  • Floor wire
  • Front seat airbag assembly LH
  • Airbag sensor assembly

Comes on

Applicable

B1826

Open in Side Squib (LH) Circuit

One of the following conditions is met:

  • The airbag sensor assembly detects an open circuit signal in the front side squib LH circuit for 2 seconds.
  • A front seat airbag assembly LH malfunction.
  • An airbag sensor assembly malfunction.
  • Floor wire
  • Front seat airbag assembly LH
  • Airbag sensor assembly

Comes on

Applicable

B1827

Short in Side Squib (LH) Circuit (to Ground)

One of the following conditions is met:

  • The airbag sensor assembly detects a short circuit to ground signal in the front side squib LH circuit for 0.5 seconds.
  • A front seat airbag assembly LH malfunction.
  • An airbag sensor assembly malfunction.
  • Floor wire
  • Front seat airbag assembly LH
  • Airbag sensor assembly

Comes on

Applicable

B1828

Short in Side Squib (LH) Circuit (to +B)

One of the following conditions is met:

  • The airbag sensor assembly detects a short circuit to B+ signal in the front side squib LH circuit for 0.5 seconds.
  • A front seat airbag assembly LH malfunction.
  • An airbag sensor assembly malfunction.
  • Floor wire
  • Front seat airbag assembly LH
  • Airbag sensor assembly

Comes on

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

HINT:

To perform the simulation method, enter check mode (signal check) with the Techstream (Click here ), and then wiggle each connector of the airbag system or drive the vehicle on various types of road (Click here ).

PROCEDURE

1.

CHECK CONNECTORS

(a) Turn the ignition switch off.

*1

Front Seat Airbag Assembly LH

*2

Airbag Sensor Assembly

*3

Floor Wire

(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 front seat airbag assembly LH and airbag sensor assembly.

OK:

The connectors are properly connected.

HINT:

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

(d) Disconnect the connectors from the front seat airbag assembly LH and airbag sensor assembly.

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

OK:

The terminals are not deformed or damaged.

(f) Check that the short springs of the activation prevention mechanism of the floor wire connector are not deformed or damaged.

OK:

The short springs are not deformed or damaged.

NG

REPLACE FLOOR WIRE

OK

2.

CHECK FRONT SEAT AIRBAG ASSEMBLY LH

(a) Connect the connector to the airbag sensor assembly.

*1

Front Seat Airbag Assembly LH

*2

Airbag Sensor Assembly

*3

SST

*a

Front view of wire harness connector

(to Front Seat Airbag Assembly LH)

(b) Connect the red wire side of SST (resistance: 2.1 Ω) to connector C.

CAUTION:

Never connect the tester to the front seat airbag assembly LH for measurement, as this may lead to a serious injury due to airbag deployment.

NOTICE:

  • Do not forcibly insert SST into the terminals of the connector when connecting SST.
  • Insert SST straight into the terminals of the connector.

SST: 09843-18061

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

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

(e) Clear the DTCs.

Click here

(f) Turn the ignition switch off.

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

(h) Check for DTCs.

Click here

Result

Proceed to

DTC B1825, B1826, B1827 or B1828 is not output

A

DTC B1825, B1826, B1827 or B1828 is output

B

HINT:

Codes other than DTC B1800/51, B1801/51, B1802/51 and B1803/51 may be output at this time, but they are not related to this check.

(i) Turn the ignition switch off.

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

(k) Disconnect SST from connector C.

A

REPLACE FRONT SEAT AIRBAG ASSEMBLY LH

B

3.

CHECK FLOOR WIRE

(a) Disconnect the floor wire from the airbag sensor assembly.

*1

Front Seat Airbag Assembly LH

*2

Airbag Sensor Assembly

*3

Floor Wire

*a

Front view of wire harness connector

(to Front Seat Airbag Assembly LH)

Release the activation prevention mechanism

(b) Check for a short to B+ in the circuit.

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

(2) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

P12-1 (SFL+) - Body ground

Ignition switch ON

Below 1 V

P12-2 (SFL-) - Body ground

Ignition switch ON

Below 1 V

(4) Turn the ignition switch off.

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

(c) Check for an open in the circuit.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

P12-1 (SFL+) - P12-2 (SFL-)

Always

Below 1 Ω

(d) Check for a short to ground in the circuit.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

P12-1 (SFL+) - Body ground

Always

1 MΩ or higher

P12-2 (SFL-) - Body ground

Always

1 MΩ or higher

(e) Check for a short in the circuit.

(1) Release the activation prevention mechanism built into connector B.

Click here

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

P12-1 (SFL+) - P12-2 (SFL-)

Always

1 MΩ or higher

(3) Restore the released activation prevention mechanism of connector B to the original condition.

NG

REPLACE FLOOR WIRE

OK

4.

CHECK DTC

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

*1

Front Seat Airbag Assembly LH

*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 B1825, B1826, B1827 or B1828 is not output

A

DTC B1825, B1826, B1827 or B1828 is output

B

HINT:

Codes other than DTC B1825, B1826, B1827 and B1828 may be output at this time, but they are not related to this check.

A

USE SIMULATION METHOD TO CHECK

B

REPLACE AIRBAG SENSOR ASSEMBLY

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