Last Modified: 08-21-2023 6.11:8.1.0 Doc ID: RM100000001BKCT
Model Year Start: 2019 Model: Avalon Prod Date Range: [04/2018 -           ]
Title: SUPPLEMENTAL RESTRAINT SYSTEMS: AIRBAG SYSTEM (for Gasoline Model): B1925-B1928; Short in Rear P/T Squib (LH) Circuit; 2019 - 2022 MY Avalon [04/2018 -        ]

DTC

B1925

Short in Rear P/T Squib (LH) Circuit

DTC

B1926

Open in Rear P/T Squib (LH) Circuit

DTC

B1927

Short in Rear P/T Squib (LH) Circuit (to Ground)

DTC

B1928

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

DESCRIPTION

The rear pretensioner squib LH circuit consists of the airbag ECU assembly and rear seat 3 point type belt assembly LH.

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 rear pretensioner squib LH circuit.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Test Mode / Check Mode

B1925

Short in Rear P/T Squib (LH) Circuit
  • The airbag ECU assembly detects a line short in the rear pretensioner squib LH circuit during the primary check.
  • Rear pretensioner squib LH malfunction
  • Airbag ECU assembly malfunction
  • Floor wire
  • Rear pretensioner squib LH (Rear seat 3 point type belt assembly LH)
  • Airbag ECU assembly

Comes on

Applies to check mode

B1926

Open in Rear P/T Squib (LH) Circuit
  • The airbag ECU assembly detects an open in the rear pretensioner squib LH circuit.
  • Rear pretensioner squib LH malfunction
  • Airbag ECU assembly malfunction
  • Floor wire
  • Rear pretensioner squib LH (Rear seat 3 point type belt assembly LH)
  • Airbag ECU assembly

Comes on

Applies to check mode

B1927

Short in Rear P/T Squib (LH) Circuit (to Ground)
  • The airbag ECU assembly detects a short to ground in the rear pretensioner squib LH circuit.
  • Rear pretensioner squib LH malfunction
  • Airbag ECU assembly malfunction
  • Floor wire
  • Rear pretensioner squib LH (Rear seat 3 point type belt assembly LH)
  • Airbag ECU assembly

Comes on

Applies to check mode

B1928

Short in Rear P/T Squib (LH) Circuit (to +B)
  • The airbag ECU assembly detects a short to B+ in the rear pretensioner squib LH circuit.
  • Rear pretensioner squib LH malfunction
  • Airbag ECU assembly malfunction
  • Floor wire
  • Rear pretensioner squib LH (Rear seat 3 point type belt assembly LH)
  • 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 2019 - 2022 MY Avalon Avalon HV [04/2018 -        ]; INTRODUCTION: REPAIR INSTRUCTION: PRECAUTION

HINT:

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

    Click here 2019 - 2022 MY Avalon [04/2018 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: AIRBAG SYSTEM (for Gasoline Model): CHECK MODE PROCEDURE

  • 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 2019 - 2022 MY Avalon Avalon HV [04/2018 -        ]; INTRODUCTION: HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS: HOW TO PROCEED WITH TROUBLESHOOTING

PROCEDURE

1.

CHECK CONNECTORS

(a) Turn the engine switch off.

*1

Rear Seat 3 Point Type Belt Assembly LH

*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 rear seat 3 point type belt assembly LH 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 rear seat 3 point type belt assembly LH 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 rear seat 3 point type belt assembly LH 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 REAR SEAT 3 POINT TYPE BELT ASSEMBLY LH

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

*1

Rear Seat 3 Point Type Belt Assembly LH

*2

Airbag ECU Assembly

*a

Front view of wire harness connector

(to Rear Seat 3 Point Type Belt Assembly LH)

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

CAUTION:

Never connect a tester to the rear seat 3 point type belt assembly LH 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 B1925, B1926, B1927 or B1928 is not output.

HINT:

Codes other than DTCs B1925, B1926, B1927 and B1928 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 REAR SEAT 3 POINT TYPE BELT ASSEMBLY LH 2019 - 2020 MY Avalon Avalon HV [04/2018 - 08/2020]; SEAT BELT: REAR SEAT OUTER BELT ASSEMBLY: REMOVAL 2021 MY Avalon Avalon HV [08/2020 - 08/2021]; SEAT BELT: REAR SEAT OUTER BELT ASSEMBLY: REMOVAL 2022 MY Avalon Avalon HV [08/2021 -        ]; SEAT BELT: REAR SEAT OUTER BELT ASSEMBLY: REMOVAL

NG

3.

CHECK FLOOR WIRE

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

*1

Rear Seat 3 Point Type Belt Assembly LH

*2

Airbag ECU Assembly

*3

Floor Wire

*a

Front view of wire harness connector

(to Rear Seat 3 Point Type Belt Assembly LH)

(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

K49-1 (RL+) - Body ground

Engine switch on (IG)

Below 1 V

K49-2 (RL-) - 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

K49-1 (RL+) - K49-2 (RL-)

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

K49-1 (RL+) - Body ground

Always

1 MΩ or higher

K49-2 (RL-) - 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 2019 - 2022 MY Avalon [04/2018 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: AIRBAG SYSTEM (for Gasoline Model): SYSTEM DESCRIPTION

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

K49-1 (RL+) - K49-2 (RL-)

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 rear seat 3 point type belt assembly LH and airbag ECU assembly.

*1

Rear Seat 3 Point Type Belt Assembly LH

*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 B1925, B1926, B1927 or B1928 is not output.

HINT:

Codes other than DTCs B1925, B1926, B1927 and B1928 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 2019 - 2020 MY Avalon Avalon HV [04/2018 - 08/2020]; SUPPLEMENTAL RESTRAINT SYSTEMS: CENTER AIRBAG SENSOR ASSEMBLY: REMOVAL 2021 MY Avalon Avalon HV [08/2020 - 08/2021]; SUPPLEMENTAL RESTRAINT SYSTEMS: CENTER AIRBAG SENSOR ASSEMBLY: REMOVAL 2022 MY Avalon Avalon HV [08/2021 -        ]; SUPPLEMENTAL RESTRAINT SYSTEMS: CENTER AIRBAG SENSOR ASSEMBLY: REMOVAL