Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Short in P/T Squib (RH) Circuit (B1900-B1903)

DESCRIPTION

The front pretensioner squib RH circuit consists of the airbag ECU assembly and front seat outer belt assembly RH.

The airbag ECU assembly uses this circuit to deploy the pretensioner when deployment conditions are met.

These DTCs are stored when a malfunction is detected in the front pretensioner squib RH circuit.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Test Mode / Check Mode

B1900

Short in P/T Squib (RH) Circuit

  • The airbag ECU assembly detects a line short in the front pretensioner squib RH circuit during the primary check.
  • Front pretensioner squib RH malfunction
  • Airbag ECU assembly malfunction
  • Floor wire
  • Front pretensioner squib RH (Front seat outer belt assembly RH)
  • Airbag ECU assembly

Comes on

Applies to check mode

B1901

Open in P/T Squib (RH) Circuit

  • The airbag ECU assembly detects an open in the front pretensioner squib RH circuit.
  • Front pretensioner squib RH malfunction
  • Airbag ECU assembly malfunction
  • Floor wire
  • Front pretensioner squib RH (Front seat outer belt assembly RH)
  • Airbag ECU assembly

Comes on

Applies to check mode

B1902

Short in P/T Squib (RH) Circuit (to Ground)

  • The airbag ECU assembly detects a short to ground in the front pretensioner squib RH circuit.
  • Front pretensioner squib RH malfunction
  • Airbag ECU assembly malfunction
  • Floor wire
  • Front pretensioner squib RH (Front seat outer belt assembly RH)
  • Airbag ECU assembly

Comes on

Applies to check mode

B1903

Short in P/T Squib (RH) Circuit (to +B)

  • The airbag ECU assembly detects a short to B+ in the front pretensioner squib RH circuit.
  • Front pretensioner squib RH malfunction
  • Airbag ECU assembly malfunction
  • Floor wire
  • Front pretensioner squib RH (Front seat outer belt assembly RH)
  • Airbag ECU assembly

Comes on

Applies to check mode

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

After turning the engine 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

HINT:

  • Perform the simulation method by selecting check mode (Signal Check) using the Techstream.

    Click here

  • After selecting check mode (Signal Check), perform the simulation method by wiggling each connector of the airbag system or driving the vehicle on a city road or rough road.

    Click here

PROCEDURE

1.

CHECK CONNECTORS

(a) Turn the engine switch off.

*1

Front Seat Outer Belt Assembly RH

*2

Airbag ECU Assembly

*3

Floor Wire

(b) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(c) Check that the connectors are properly connected to the front seat outer belt assembly RH and airbag ECU 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 outer belt assembly RH and airbag ECU 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 floor wire connector (on the front seat outer belt assembly RH side) is not loose, deformed or damaged.

OK:

The airbag connector locking button is not disengaged, and the claw of the lock is not deformed or damaged.

(g) 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 OUTER BELT ASSEMBLY RH

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

*1

Front Seat Outer Belt Assembly RH

*2

Airbag ECU Assembly

*a

Front view of wire harness connector

(to Front Seat Outer Belt Assembly RH)

(b) Connect SST (resistance 2.1 Ω) to connector C.

CAUTION:

Never connect a tester to the front seat outer belt assembly RH for measurement, as this may lead to a serious injury due to pretensioner deployment.

NOTICE:

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

SST: 09843-18061

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

(d) Turn the engine switch on (IG), and wait for at least 60 seconds.

(e) Clear the DTCs stored in memory.

Body Electrical > SRS Airbag > Clear DTCs

(f) Turn the engine switch off.

(g) Turn the engine switch on (IG), and wait for at least 60 seconds.

(h) Check for DTCs.

Body Electrical > SRS Airbag > Trouble Codes

OK:

DTC B1900, B1901, B1902 or B1903 is not output.

HINT:

Codes other than DTCs B1900, B1901, B1902 and B1903 may be output at this time, but they are not related to this check.

(i) Turn the engine switch off.

(j) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(k) Disconnect SST from connector C.

OK

REPLACE FRONT SEAT OUTER BELT ASSEMBLY RH

NG

3.

CHECK FLOOR WIRE

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

*1

Front Seat Outer Belt Assembly RH

*2

Airbag ECU Assembly

*3

Floor Wire

*a

Front view of wire harness connector

(to Front Seat Outer Belt Assembly RH)

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

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

(2) Turn the engine switch on (IG).

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

K46-1 (R+) - Body ground

Engine switch on (IG)

Below 1 V

K46-2 (R-) - Body ground

Engine switch on (IG)

Below 1 V

(4) Turn the engine switch off.

(5) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(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

K46-1 (R+) - K46-2 (R-)

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

K46-1 (R+) - Body ground

Always

1 MΩ or higher

K46-2 (R-) - 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

K46-1 (R+) - K46-2 (R-)

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 outer belt assembly RH and airbag ECU assembly.

*1

Front Seat Outer Belt Assembly RH

*2

Airbag ECU Assembly

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

(c) Turn the engine switch on (IG), and wait for at least 60 seconds.

(d) Clear the DTCs stored in memory.

Body Electrical > SRS Airbag > Clear DTCs

(e) Turn the engine switch off.

(f) Turn the engine switch on (IG), and wait for at least 60 seconds.

(g) Check for DTCs.

Body Electrical > SRS Airbag > Trouble Codes

OK:

DTC B1900, B1901, B1902 or B1903 is not output.

HINT:

Codes other than DTCs B1900, B1901, B1902 and B1903 may be output at this time, but they are not related to this check.

OK

USE SIMULATION METHOD TO CHECK

NG

REPLACE AIRBAG ECU ASSEMBLY

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