Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Front Airbag Sensor Lost Communication (LH) (B1617,B1618)

Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual / Vehicle Interior / Supplemental Restraint Systems / Airbag System / Front Airbag Sensor Lost Communication (LH) (B1617,B1618)

DESCRIPTION

The front airbag sensor LH circuit consists of the airbag sensor assembly and front airbag sensor LH.

The front airbag sensor LH detects impacts to the vehicle and sends signals to the airbag sensor assembly to determine if the airbags, pretensioners and selectable force limiter should be deployed.

These DTCs are stored when a malfunction is detected in the front airbag sensor LH circuit.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Test Mode / Check Mode

B1617

Front Airbag Sensor Lost Communication (LH)
  • The airbag sensor assembly detects a line short, short to ground or B+, or an open in the front airbag sensor LH circuit.
  • Front airbag sensor LH malfunction
  • Airbag sensor assembly malfunction
  • Instrument panel wire
  • Engine room main wire
  • Front airbag sensor LH
  • Airbag sensor assembly

Comes on

Does not apply to test/check mode

B1618

Front Airbag Sensor Initialization Error (LH)
  • The airbag sensor assembly detects a line short, short to ground or B+, or an open in the front airbag sensor LH circuit.
  • Front airbag sensor LH malfunction
  • Airbag sensor assembly malfunction
  • Instrument panel wire
  • Engine room main wire
  • Front airbag sensor LH
  • 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 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 and front airbag sensor LH. Also check that the connectors that link the engine room main wire and instrument panel wire are properly connected.

OK:

The connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY
OK

2.

CHECK CONNECTORS

(a) Disconnect the connectors from the airbag sensor assembly and front airbag sensor LH. Also disconnect the connectors that link the engine room main wire and instrument panel wire.

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

OK:

The terminals are not deformed or damaged.

NG

REPLACE INSTRUMENT PANEL WIRE OR ENGINE ROOM MAIN WIRE
OK

3.

CHECK FRONT AIRBAG SENSOR LH CIRCUIT

(a) Connect the connectors that link the engine room main wire and instrument panel wire.

*1

Front Airbag Sensor LH

*2

Airbag Sensor Assembly

*3

Engine Room Main Wire

*4

Instrument Panel Wire

*5

Service Wire

*a

Front view of wire harness connector

(to Airbag Sensor Assembly)

*b

Front view of wire harness connector

(to Front Airbag Sensor LH)

(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

A7-2 (+SL) - Body ground

Engine switch on (IG)

Below 1 V

A7-1 (-SL) - 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 30 (+SL) and 31 (-SL) 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

A7-2 (+SL) - A7-1 (-SL)

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

A7-2 (+SL) - A7-1 (-SL)

Always

1 MΩ or higher

A7-2 (+SL) - Body ground

Always

1 MΩ or higher

A7-1 (-SL) - Body ground

Always

1 MΩ or higher
NG

GO TO STEP 5

OK

4.

CHECK FRONT AIRBAG SENSOR LH

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

*1

Front Airbag Sensor RH

*2

Airbag Sensor Assembly

(b) Interchange the front airbag sensor LH with RH 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 B1612, B1613, B1617 and B1618 may be output at this time, but they are not related to this check.

Result

Proceed to

DTCs B1612, B1613, B1617 and B1618 are not output.

A

DTC B1617 or B1618 is output.

B

DTC B1612 or B1613 is 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 front airbag sensor LH and RH to their original positions and connect the connectors.

A

USE SIMULATION METHOD TO CHECK

B

REPLACE AIRBAG SENSOR ASSEMBLY

C

REPLACE FRONT AIRBAG SENSOR LH

5.

CHECK INSTRUMENT PANEL WIRE

(a) Disconnect the instrument panel wire connector from the engine room main wire.

*1

Front Airbag Sensor LH

*2

Airbag Sensor Assembly

*3

Engine Room Main Wire

*4

Instrument Panel Wire

*5

Service Wire

*a

Front view of wire harness connector

(to Airbag Sensor Assembly)

*b

Front view of wire harness connector

(to Engine Room Main Wire)

(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

AJ1-3 (+SL) - Body ground

Engine switch on (IG)

Below 1 V

AJ1-4 (-SL) - 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 30 (+SL) and 31 (-SL) 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

AJ1-3 (+SL) - AJ1-4 (-SL)

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

AJ1-3 (+SL) - AJ1-4 (-SL)

Always

1 MΩ or higher

AJ1-3 (+SL) - Body ground

Always

1 MΩ or higher

AJ1-4 (-SL) - Body ground

Always

1 MΩ or higher
OK

REPLACE ENGINE ROOM MAIN WIRE
NG

REPLACE INSTRUMENT PANEL WIRE
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