Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Curtain Shield Airbag Sensor Initialization Error (RH) (B1633)

DESCRIPTION

The side collision sensor RH circuit (bus 1) consists of the airbag sensor assembly, door side airbag sensor RH and rear airbag sensor RH.

The door side airbag sensor RH and rear airbag sensor RH detect impacts to the vehicle and send signals to the airbag sensor assembly to determine if the airbags, pretensioners and selectable force limiter should be deployed.

DTC B1633 is stored when a malfunction is detected in the side collision sensor RH circuit (bus 1).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Test Mode / Check Mode
B1633	Curtain Shield Airbag Sensor Initialization Error (RH)	The airbag sensor assembly detects a line short, short to ground or B+, or an open in the side collision sensor RH circuit (bus 1). Rear airbag sensor RH malfunction Airbag sensor assembly malfunction	Floor wire Front door wire RH Rear airbag sensor RH Airbag sensor assembly	Comes on	Does not apply to test/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

PROCEDURE

1.	CHECK HISTORY DTC

(a) Check for history DTCs.

Body Electrical > SRS Airbag > Trouble Codes

HINT:

Codes other than history DTC B1632 may be output at this time, but they are not related to this check.

Result	Proceed to
History DTC B1632 is not output.	A
History DTC B1632 is output.	B

B

GO TO DTC B1632

A

2.	CHECK CONNECTION OF CONNECTORS

(a) Turn the engine switch off.

(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 airbag sensor assembly, door side airbag sensor RH and rear airbag sensor RH. Also check that the connectors that link the floor wire and front door wire RH are properly connected.

OK:

The connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY

OK

3.	CHECK CONNECTORS

(a) Disconnect the connectors from the airbag sensor assembly, door side airbag sensor RH and rear airbag sensor RH. Also disconnect the connectors that link the floor wire and front door wire RH.

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

OK:

The terminals are not deformed or damaged.

NG

REPLACE FLOOR WIRE OR FRONT DOOR WIRE RH

OK

4.	CHECK FLOOR WIRE

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

*1 Rear Airbag Sensor RH *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 Rear Airbag Sensor RH)

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
R15-4 (BCR+) - Body ground	Engine switch on (IG)	Below 1 V
R15-3 (BCR-) - Body ground	Engine switch on (IG)	Below 1 V

(d) Turn the engine switch off.

(e) 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.

(f) Using a service wire, connect terminals 25 (BBR+) and 26 (BBR-) 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
R15-4 (BCR+) - R15-3 (BCR-)	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
R15-4 (BCR+) - R15-3 (BCR-)	Always	1 MΩ or higher
R15-4 (BCR+) - Body ground	Always	1 MΩ or higher
R15-3 (BCR-) - Body ground	Always	1 MΩ or higher

NG

REPLACE FLOOR WIRE

OK

5.	CHECK WIRE HARNESS

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

*1 Door Side Airbag Sensor RH *2 Rear Airbag Sensor RH *3 Front Door Wire RH *4 Floor Wire *5 Service Wire *a Front view of wire harness connector (to Rear Airbag Sensor RH) *b Front view of wire harness connector (to Door Side Airbag Sensor RH)

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

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
R15-1 (BDR+) - Body ground	Engine switch on (IG)	Below 1 V
R15-2 (BDR-) - Body ground	Engine switch on (IG)	Below 1 V

(e) Turn the engine switch off.

(f) 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.

(g) Using a service wire, connect terminals 2 (BDR+) and 1 (BDR-) 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
R15-1 (BDR+) - R15-2 (BDR-)	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
R15-1 (BDR+) - R15-2 (BDR-)	Always	1 MΩ or higher
R15-1 (BDR+) - Body ground	Always	1 MΩ or higher
R15-2 (BDR-) - Body ground	Always	1 MΩ or higher

NG

GO TO STEP 7

OK

6.	CHECK REAR AIRBAG SENSOR RH

(a) Connect the connectors to the door side airbag sensor RH and airbag sensor assembly.

*1 Rear Airbag Sensor LH *2 Airbag Sensor Assembly

(b) Interchange the rear airbag sensor RH with LH and connect the connectors.

(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

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

(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) Return the rear airbag sensor RH and LH to their original positions and connect the connectors.

A

REPLACE AIRBAG SENSOR ASSEMBLY

B

REPLACE REAR AIRBAG SENSOR RH

C

USE SIMULATION METHOD TO CHECK

7.	CHECK FLOOR WIRE

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

*1 Door Side Airbag Sensor RH *2 Rear Airbag Sensor RH *3 Front Door Wire RH *4 Floor Wire *5 Service Wire *a Front view of wire harness connector (to Rear Airbag Sensor RH) *b Front view of wire harness connector (to Front Door Wire RH)

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

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
MR1-31 (BDR+) - Body ground	Engine switch on (IG)	Below 1 V
MR1-13 (BDR-) - Body ground	Engine switch on (IG)	Below 1 V

(e) Turn the engine switch off.

(f) 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.

(g) Using a service wire, connect terminals 1 (BDR+) and 2 (BDR-) 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
MR1-31 (BDR+) - MR1-13 (BDR-)	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
MR1-31 (BDR+) - MR1-13 (BDR-)	Always	1 MΩ or higher
MR1-31 (BDR+) - Body ground	Always	1 MΩ or higher
MR1-13 (BDR-) - Body ground	Always	1 MΩ or higher

OK

REPLACE FRONT DOOR WIRE RH

NG

REPLACE FLOOR WIRE