SUPPLEMENTAL RESTRAINT SYSTEMS: AIRBAG SYSTEM (for HV Model): B1638; Curtain Shield Airbag Sensor Initialization Error (LH); 2020 - 2022 MY Corolla Corolla HV [01/2019

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM100000001G4PM
Model Year Start: 2020	Model: Corolla	Prod Date Range: [01/2019 - 09/2022]
Title: SUPPLEMENTAL RESTRAINT SYSTEMS: AIRBAG SYSTEM (for HV Model): B1638; Curtain Shield Airbag Sensor Initialization Error (LH); 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

DTC

B1638

Curtain Shield Airbag Sensor Initialization Error (LH)

DESCRIPTION

The side collision sensor LH circuit (bus 1) consists of the airbag sensor assembly, side airbag pressure sensor LH and side No. 2 airbag sensor LH.

The side airbag pressure sensor LH and side No. 2 airbag sensor LH detect impacts to the vehicle and send signals to the airbag sensor assembly to determine if the airbags and pretensioners should be deployed.

DTC B1638 is stored when a malfunction is detected in the side collision sensor LH circuit (bus 1).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Test Mode / Check Mode
B1638	Curtain Shield Airbag Sensor Initialization Error (LH)	The airbag sensor assembly detects a line short, short to ground or B+, or an open in the side collision sensor LH circuit (bus 1). Side No. 2 airbag sensor LH malfunction Airbag sensor assembly malfunction	Floor wire Front door wire LH Side No. 2 airbag sensor LH Airbag sensor assembly	Comes on	Does not apply to test/check mode

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

Click here

PROCEDURE

1.	CHECK HISTORY DTC

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

(b) Check for history DTCs.

Body Electrical > SRS Airbag > Trouble Codes

HINT:

Codes other than history DTC B1637 may be output at this time, but they are not related to this check.

Result	Proceed to
History DTC B1637 is not output.	A
History DTC B1637 is output.	B

GO TO DTC B1637

2.	CHECK CONNECTION OF CONNECTORS

(a) Turn the power switch off.

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

CAUTION:

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

(c) Check that the connectors are properly connected to the airbag sensor assembly, side airbag pressure sensor LH and side No. 2 airbag sensor LH. Also check that the connectors that link the floor wire and front door wire LH are properly connected.

OK:

The connectors are properly connected.

CONNECT CONNECTORS PROPERLY

3.	CHECK CONNECTORS

(a) Disconnect the connectors from the airbag sensor assembly, side airbag pressure sensor LH and side No. 2 airbag sensor LH. Also disconnect the connectors that link the floor wire and front door wire LH.

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

OK:

The terminals are not deformed or damaged.

REPLACE FLOOR WIRE OR FRONT DOOR WIRE LH

4.	CHECK FLOOR WIRE

(a) Connect the cable to the negative (-) auxiliary battery terminal.

*1	Side No. 2 Airbag Sensor LH
*2	Airbag Sensor Assembly
*3	Floor Wire
*4	Service Wire
*a	Front view of wire harness connector (to Airbag Sensor Assembly)
*b	Front view of wire harness connector (to Side No. 2 Airbag Sensor LH)

(b) Turn the power switch on (IG).

Standard Voltage:

Tester Connection	Condition	Specified Condition
O11-4 (BCL+) - Body ground	Power switch on (IG)	Below 1 V
O11-3 (BCL-) - Body ground	Power switch on (IG)	Below 1 V

(d) Turn the power switch off.

(e) Disconnect the cable from the negative (-) auxiliary battery terminal.

CAUTION:

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

(f) Using a service wire, connect terminals 32 (BBL+) and 31 (BBL-) of connector B.

NOTICE:

Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
O11-4 (BCL+) - O11-3 (BCL-)	Always	Below 1 Ω

(h) Disconnect the service wire from connector B.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
O11-4 (BCL+) - O11-3 (BCL-)	Always	1 MΩ or higher
O11-4 (BCL+) - Body ground	Always	1 MΩ or higher
O11-3 (BCL-) - Body ground	Always	1 MΩ or higher

REPLACE FLOOR WIRE

5.	CHECK WIRE HARNESS

(a) Connect the connectors that link the floor wire and front door wire LH.

*1	Side Airbag Pressure Sensor LH
*2	Side No. 2 Airbag Sensor LH
*3	Front Door Wire LH
*4	Floor Wire
*5	Service Wire
*a	Front view of wire harness connector (to Side No. 2 Airbag Sensor LH)
*b	Front view of wire harness connector (to Side Airbag Pressure Sensor LH)

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
O11-1 (BDL+) - Body ground	Power switch on (IG)	Below 1 V
O11-2 (BDL-) - Body ground	Power switch on (IG)	Below 1 V

(e) Turn the power switch off.

(f) Disconnect the cable from the negative (-) auxiliary battery terminal.

CAUTION:

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

(g) Using a service wire, connect terminals 2 (BDL+) and 1 (BDL-) of connector E.

NOTICE:

Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
O11-1 (BDL+) - O11-2 (BDL-)	Always	Below 1 Ω

(i) Disconnect the service wire from connector E.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
O11-1 (BDL+) - O11-2 (BDL-)	Always	1 MΩ or higher
O11-1 (BDL+) - Body ground	Always	1 MΩ or higher
O11-2 (BDL-) - Body ground	Always	1 MΩ or higher

GO TO STEP 7

6.	CHECK SIDE NO. 2 AIRBAG SENSOR LH

(a) Connect the connectors to the side airbag pressure sensor LH and airbag sensor assembly.

*1	Side No. 2 Airbag Sensor RH
*2	Airbag Sensor Assembly

(b) Interchange the side No. 2 airbag sensor LH with RH and connect the connectors.

(d) Turn the power 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 power switch off.

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

(h) Check for DTCs.

Body Electrical > SRS Airbag > Trouble Codes

HINT:

Codes other than DTCs B1633 and B1638 may be output at this time, but they are not related to this check.

Result	Proceed to
DTC B1638 is output.	A
DTC B1633 is output.	B
DTCs B1633 and B1638 are not output.	C

(i) Turn the power switch off.

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

CAUTION:

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

(k) Return the side No. 2 airbag sensor LH and RH to their original positions and connect the connectors.

REPLACE AIRBAG SENSOR ASSEMBLY

REPLACE SIDE NO. 2 AIRBAG SENSOR LH

USE SIMULATION METHOD TO CHECK

7.	CHECK FLOOR WIRE

(a) Disconnect the floor wire connector from the front door wire LH.

*1	Side Airbag Pressure Sensor LH
*2	Side No. 2 Airbag Sensor LH
*3	Front Door Wire LH
*4	Floor Wire
*5	Service Wire
*a	Front view of wire harness connector (to Side No. 2 Airbag Sensor LH)
*b	Front view of wire harness connector (to Front Door Wire LH)

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
LO1-22 (BDL+) - Body ground	Power switch on (IG)	Below 1 V
LO1-40 (BDL-) - Body ground	Power switch on (IG)	Below 1 V

(e) Turn the power switch off.

(f) Disconnect the cable from the negative (-) auxiliary battery terminal.

CAUTION:

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

(g) Using a service wire, connect terminals 1 (BDL+) and 2 (BDL-) of connector B.

NOTICE:

Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
LO1-22 (BDL+) - LO1-40 (BDL-)	Always	Below 1 Ω

(i) Disconnect the service wire from connector B.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
LO1-22 (BDL+) - LO1-40 (BDL-)	Always	1 MΩ or higher
LO1-22 (BDL+) - Body ground	Always	1 MΩ or higher
LO1-40 (BDL-) - Body ground	Always	1 MΩ or higher

REPLACE FRONT DOOR WIRE LH

REPLACE FLOOR WIRE