DTC B1855: Short in Rear Side Squib LH Circuit; DTC B1856: Open in Rear Side Squib LH Circuit; DTC B1857: Short to GND in Rear Side Squib LH Circuit; DTC B1858: Short to B+ in Rear Side Squib LH Circuit [06/2018 - ]: Procedure

CHECK CONNECTORS

Turn the engine switch off.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	Rear Seat Airbag Assembly LH
*2	Airbag ECU Assembly
*3	Floor Wire

Disconnect the cable from the negative (-) battery terminal.
WARNING:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
Check that the connectors are properly connected to the rear seat airbag 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.
Disconnect the connectors from the rear seat airbag assembly LH and airbag ECU assembly.
Check that the terminals of the connectors are not deformed or damaged.
OK

The terminals are not deformed or damaged.

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

The short springs are not deformed or damaged.

Result

Proceed to
OK
NG

Result:

REPLACE FLOOR WIRE

Result:

See step 2

CHECK REAR SEAT AIRBAG ASSEMBLY LH

Connect the connector to the airbag ECU assembly.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	Rear Seat Airbag Assembly LH
*2	Airbag ECU Assembly
*a	Front view of wire harness connector (to Rear Seat Airbag Assembly LH)

Connect SST (resistance 2.1 Ω) to connector C.
WARNING:
Never connect a tester to the rear seat airbag assembly LH for measurement, as this may lead to a serious injury due to airbag deployment.
NOTE:
- 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
Connect the cable to the negative (-) battery terminal.
Turn the engine switch on (IG), and wait for at least 60 seconds.
Clear the DTCs stored in memory.
Body Electrical > SRS Airbag > Clear DTCs
Turn the engine switch off.
Turn the engine switch on (IG), and wait for at least 60 seconds.
Check for DTCs.
Body Electrical > SRS Airbag > Trouble Codes

OK

DTC B1855, B1856, B1857 or B1858 is not output.

HINT:

Codes other than DTCs B1855, B1856, B1857 and B1858 may be output at this time, but they are not related to this check.
Turn the engine switch off.
Disconnect the cable from the negative (-) battery terminal.
WARNING:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

Disconnect SST from connector C.

Result

Proceed to
OK
NG

Result:

REPLACE REAR SEAT AIRBAG ASSEMBLY LH. Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]

Result:

See step 3

CHECK FLOOR WIRE

Disconnect the floor wire from the airbag ECU assembly.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	Rear Seat Airbag Assembly LH
*2	Airbag ECU Assembly
*3	Floor Wire
*a	Front view of wire harness connector (to Rear Seat Airbag Assembly LH)

Check for a short to B+ in the circuit.

Connect the cable to the negative (-) battery terminal.
Turn the engine switch on (IG).

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

Standard Voltage

Tester Connection	Condition	Specified Condition
N56-1 (SRL+) - Body ground	Engine switch on (IG)	Below 1 V
N56-2 (SRL-) - Body ground	Engine switch on (IG)	Below 1 V

Turn the engine switch off.
Disconnect the cable from the negative (-) battery terminal.
WARNING:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

Check for an open in the circuit.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
N56-1 (SRL+) - N56-2 (SRL-)	Always	Below 1 Ω

Check for a short to ground in the circuit.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
N56-1 (SRL+) - Body ground	Always	1 MΩ or higher
N56-2 (SRL-) - Body ground	Always	1 MΩ or higher

Check for a short in the circuit.

Release the activation prevention mechanism built into connector B.
Refer to SYSTEM DESCRIPTION [06/2018 - 08/2021] , or refer to SYSTEM DESCRIPTION [08/2021 - ]

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

Standard Resistance

Tester Connection	Condition	Specified Condition
N56-1 (SRL+) - N56-2 (SRL-)	Always	1 MΩ or higher

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

Result

Proceed to
OK
NG

Result:

REPLACE FLOOR WIRE

Result:

See step 4

CHECK DTC

Connect the connectors to the rear seat airbag assembly LH and airbag ECU assembly.

*1	Rear Seat Airbag Assembly LH
*2	Airbag ECU Assembly

Connect the cable to the negative (-) battery terminal.
Turn the engine switch on (IG), and wait for at least 60 seconds.
Clear the DTCs stored in memory.
Body Electrical > SRS Airbag > Clear DTCs
Turn the engine switch off.
Turn the engine switch on (IG), and wait for at least 60 seconds.

Check for DTCs.

Body Electrical > SRS Airbag > Trouble Codes

DTC B1855, B1856, B1857 or B1858 is not output.

HINT:

Codes other than DTCs B1855, B1856, B1857 and B1858 may be output at this time, but they are not related to this check.

Result

Proceed to
OK
NG

Result:

USE SIMULATION METHOD TO CHECK. Refer to HOW TO PROCEED WITH TROUBLESHOOTING [06/2018 - ]

Result:

REPLACE AIRBAG ECU ASSEMBLY. Refer to REMOVAL [06/2018 - 08/2020] , or refer to REMOVAL [08/2020 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]