Lexus IS250 IS220d GSE20 ALE20 - SUPPLEMENTAL RESTRAINT SYSTEM

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK REAR SEAT OUTER BELT ASSEMBLY (DRIVER SIDE REAR PRETENSIONER SQUIB)

CHECK CONNECTOR

CHECK FLOOR WIRE NO. 2 (DRIVER SIDE REAR PRETENSIONER SQUIB CIRCUIT)

CHECK CENTER AIRBAG SENSOR ASSEMBLY

DTC B1920/77 Short in Driver Side Rear Pretensioner Squib Circuit

DTC B1921/77 Open in Rear Pretensioner Squib RH Circuit

DTC B1922/77 Short to GND in Rear Pretensioner Squib RH Circuit

DTC B1923/77 Short to B+ in Rear Pretensioner Squib RH Circuit

DESCRIPTION

The driver side rear pretensioner squib circuit consists of the center airbag sensor assembly and the rear seat outer belt assembly (driver side).


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


These DTCs are recorded when a malfunction is detected in the driver side rear pretensioner squib circuit.

DTC No.DTC Detection ConditionTrouble Area
B1920/77
The center airbag sensor assembly receives a line short circuit signal 5 times in the driver side rear pretensioner squib circuit during primary check.
Driver side rear pretensioner squib malfunction
Center airbag sensor assembly malfunction
Floor wire No. 2
Rear seat outer belt assembly (Driver side rear pretensioner squib)
Center airbag sensor assembly
B1921/77
The center airbag sensor assembly receives an open circuit signal in the driver side rear pretensioner squib circuit for 2 seconds.
Driver side rear pretensioner squib malfunction
Center airbag sensor assembly malfunction
Floor wire No. 2
Rear seat outer belt assembly (Driver side rear pretensioner squib)
Center airbag sensor assembly
B1922/77
The center airbag sensor assembly receives a short circuit to ground signal in the driver side rear pretensioner squib circuit for 0.5 seconds.
Driver side rear pretensioner squib malfunction
Center airbag sensor assembly malfunction
Floor wire No. 2
Rear seat outer belt assembly (Driver side rear pretensioner squib)
Center airbag sensor assembly
B1923/77
The center airbag sensor assembly receives a short circuit to B+ signal in the driver side rear pretensioner squib circuit for 0.5 seconds.
Driver side rear pretensioner squib malfunction
Center airbag sensor assembly malfunction
Floor wire No. 2
Rear seat outer belt assembly (Driver side rear pretensioner squib)
Center airbag sensor assembly

WIRING DIAGRAM

Dtc B1920/77 Short In Driver Side Rear Pretensioner Squib Circuit. SUPPLEMENTAL RESTRAINT SYSTEM. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

  • HINT:
Perform the simulation method by selecting the "check mode" (signal check) with the intelligent tester .
After selecting the "check mode" (signal check), perform the simulation method by wiggling each connector of the airbag system or driving the vehicle on a city or rough road .
1.CHECK REAR SEAT OUTER BELT ASSEMBLY (DRIVER SIDE REAR PRETENSIONER SQUIB)
Dtc B1920/77 Short In Driver Side Rear Pretensioner Squib Circuit. SUPPLEMENTAL RESTRAINT SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Turn the engine switch off.

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

Disconnect the connectors from the rear seat outer belt assembly (driver side).

Connect the white wire side of SST (resistance 2.1 Ω) to connector "C".

  • CAUTION:
  • Never connect a tester to the rear seat outer belt assembly (driver side rear pretensioner squib) for measurement, as this may lead to a serious injury due to airbag deployment.
  • NOTICE:
Do not forcibly insert the SST into the terminals of the connector when connecting.
Insert straight the SST into the terminals of the connector.

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

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

Clear the DTCs stored in the memory .

Turn the engine switch off.

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

Check for DTCs .

  • OK:
  • DTC B1920, B1921, B1922, B1923 or 77 is not output.
  • HINT:
  • Codes other than DTC B1920, B1921, B1922, B1923 and 77 may be output at this time, but they are not related to this check.
NG
REPLACE REAR SEAT OUTER BELT ASSEMBLY (DRIVER SIDE)
OK
2.CHECK CONNECTOR

Turn the engine switch off.

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

Disconnect the SST from connector "C".

Check that the floor wire No. 2 connector (on the rear seat outer belt assembly (driver side) side) is not damaged.

  • OK:
  • The lock button is not disengaged, or the claw of the lock is not deformed or damaged.
NG
REPAIR OR REPLACE FLOOR WIRE NO. 2
OK
3.CHECK FLOOR WIRE NO. 2 (DRIVER SIDE REAR PRETENSIONER SQUIB CIRCUIT)
Dtc B1920/77 Short In Driver Side Rear Pretensioner Squib Circuit. SUPPLEMENTAL RESTRAINT SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Disconnect the connectors from the center airbag sensor assembly.

Check for a short to B+ in the circuit.


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

Turn the engine switch on (IG).

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

  • Standard voltage:
  • LHD:
  • Tester connectionConditionSpecified condition
    Q20-1 (RL+) - Body groundEngine switch on (IG)Below 1 V
    Q20-2 (RL-) - Body groundEngine switch on (IG)Below 1 V
  • RHD:
  • Tester connectionConditionSpecified condition
    P17-1 (RR+) - Body groundEngine switch on (IG)Below 1 V
    P17-2 (RR-) - Body groundEngine switch on (IG)Below 1 V

Check for an open in the circuit.


Turn the engine switch off.

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

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

  • Standard resistance:
  • LHD:
  • Tester connectionConditionSpecified condition
    Q20-1 (RL+) - Q20-2 (RL-)AlwaysBelow 1 Ω
  • RHD:
  • Tester connectionConditionSpecified condition
    P17-1 (RR+) - P17-2 (RR-)AlwaysBelow 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:
  • LHD:
  • Tester connectionConditionSpecified condition
    Q20-1 (RL+) - Body groundAlways1 MΩ or higher
    Q20-2 (RL-) - Body groundAlways1 MΩ or higher
  • RHD:
  • Tester connectionConditionSpecified condition
    P17-1 (RR+) - Body groundAlways1 MΩ or higher
    P17-2 (RR-) - Body groundAlways1 MΩ or higher

Check for a short in the circuit.


Release the activation prevention mechanism built into connector "B" .

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

  • Standard resistance:
  • LHD:
  • Tester connectionConditionSpecified condition
    Q20-1 (RL+) - Q20-2 (RL-)Always1 MΩ or higher
  • RHD:
  • Tester connectionConditionSpecified condition
    P17-1 (RR+) - P17-2 (RR-)Always1 MΩ or higher
NG
REPAIR OR REPLACE FLOOR WIRE NO. 2
OK
4.CHECK CENTER AIRBAG SENSOR ASSEMBLY
Dtc B1920/77 Short In Driver Side Rear Pretensioner Squib Circuit. SUPPLEMENTAL RESTRAINT SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Connect the connectors to the rear seat outer belt assembly (driver side) and the center airbag sensor assembly.

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

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

Clear the DTCs stored in the memory .

Turn the engine switch off.

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

Check for DTCs .

  • OK:
  • DTC B1920, B1921, B1922, B1923 or 77 is not output.
  • HINT:
  • Codes other than B1920, B1921, B1922, B1923 and 77 may be output at this time, but they are not related to this check.
NG
REPLACE CENTER AIRBAG SENSOR ASSEMBLY
OK
USE SIMULATION METHOD TO CHECK
LEXUS IS250, IS220d / GSE20 ALE20
SUPPLEMENTAL RESTRAINT SYSTEM
Lexus IS250 IS220d GSE20 ALE20
AIRBAG SYSTEM