Lexus NX: GSW Terminal Circuit Malfunction (B1243)

Lexus NX Service Manual / Vehicle Interior / Door Lock / Power Door Lock Control System / GSW Terminal Circuit Malfunction (B1243)

DESCRIPTION

If the collision door lock release function does not operate normally, or an open or short in the GSW input circuit of the main body ECU (multiplex network body ECU) is detected, DTC B1243 will be stored.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B1243

GSW Terminal Circuit Malfunction

A malfunction occurs in the GSW input circuit of the main body ECU (multiplex network body ECU).

  • Main body ECU (multiplex network body ECU)
  • Instrument panel junction block assembly
  • Airbag ECU assembly
  • Instrument panel wire

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • After the power switch is turned off, there may be a waiting time before disconnecting the negative (-) auxiliary battery terminal.

    Click here

  • When disconnecting and reconnecting the auxiliary battery

    Click here

    HINT:

    When disconnecting and reconnecting the auxiliary battery, there is an automatic learning function that completes learning when the respective system is used.

    Click here

  • If the main body ECU (multiplex network body ECU) is replaced, refer to the Smart Access System with Push-button Start (for Entry Function).

    Click here

  • When DTC B1243 is output, the collision door lock release, shift-linked automatic door lock/unlock and speed-sensitive automatic door lock functions are prohibited.
  • After replacing the airbag ECU assembly, refer to initialization.

    Click here

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Main Body > Clear DTCs
NEXT

2.

CHECK FOR DTC

(a) Recheck for DTCs.

Click here

Body Electrical > Main Body > Trouble Codes

OK:

DTC B1243 is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

3.

CHECK MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

(a) 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.

NOTICE:

Turning the power switch on (IG) with the airbag ECU assembly connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

*a

Rear view of wire harness connector

(to Airbag ECU Assembly)

(b) Disconnect the airbag ECU assembly connector.

Click here

(c) 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

Switch Condition

Specified Condition

I58-18 (GSW) - Body ground

Power switch on (IG)

2.8 to 4.2 V

OK

REPLACE AIRBAG ECU ASSEMBLY

NG

4.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - AIRBAG ECU ASSEMBLY)

(a) 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.

(b) Disconnect the 4D instrument panel junction block assembly connector.

(c) Disconnect the I58 airbag ECU assembly connector.

Click here

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4D-46 - I58-18 (GSW)

Always

Below 1 Ω

4D-46 or I58-18 (GSW) - Body ground

Always

10 kΩ or higher

NG

REPLACE INSTRUMENT PANEL WIRE

OK

5.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

(a) Remove the instrument panel junction block assembly.

Click here

(b) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

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

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

A-24 (GSW) - 4D-46

Always

Below 1 Ω

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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