Lexus NX: VSC OFF Switch Circuit

DESCRIPTION

The skid control ECU assembly is connected to the combination meter assembly via CAN communication.

Pressing the VSC OFF switch turns off TRAC operation, and pressing and holding this switch turns off TRAC and VSC operation. If TRAC and VSC operations are turned off, the TRAC OFF message will be displayed on the multi-information display and the VSC OFF indicator light will come on.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake booster with master cylinder assembly), perform initialization and calibration of the linear solenoid valve.

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PROCEDURE

1.	CHECK CAN COMMUNICATION SYSTEM

(a) Check if CAN communication system DTCs are output.

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Result	Proceed to
DTCs are not output.	A
DTCs are output.	B

B

INSPECT CAN COMMUNICATION SYSTEM

A

2.	CHECK IF SKID CONTROL ECU ASSEMBLY CONNECTOR IS SECURELY CONNECTED

(a) Check if the skid control ECU assembly (brake booster with master cylinder assembly) connector is securely connected.

OK:

The connector is securely connected.

NG

CONNECT CONNECTOR TO SKID CONTROL ECU ASSEMBLY CORRECTLY

OK

3.	READ VALUE USING TECHSTREAM (TRAC/VSC OFF MODE)

(a) Connect the Techstream to the DLC3.

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

(c) Select the Data List on the Techstream.

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Chassis > ABS/VSC/TRAC > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
TRAC/VSC Off Mode	TRAC/VSC off mode	Normal, TRAC OFF, Unknown or VSC OFF	Normal: Normal mode TRAC OFF: TRAC off mode VSC OFF: VSC off mode	Unknown: Unspecified

Chassis > ABS/VSC/TRAC > Data List

Tester Display
TRAC/VSC Off Mode

(d) Check the indicator light and mode condition on the Techstream changes according to VSC OFF switch (integration control and panel assembly) operation.

Standard:

Switch Operation	Mode Condition Display	Multi-information Display (TRAC OFF Message)	VSC OFF Indicator Light
Not pressed	Normal	Not displayed	Does not come on
Pressing the VSC OFF switch	TRAC OFF	Displayed	Does not come on
Pressing and holding the VSC OFF switch	VSC OFF	Displayed	Comes on

Result	Proceed to
Indicator light and mode condition display do not change.	A
Mode condition display is normal, but indicator light does not change.	B
Indicator light and mode condition display is normal.	C

B

INSPECT METER / GAUGE SYSTEM

C

USE SIMULATION METHOD TO CHECK

A

4.	PERFORM ACTIVE TEST USING TECHSTREAM (MULTI-INFORMATION DISPLAY AND VSC OFF INDICATOR LIGHT)

(a) Select the Active Test on the Techstream.

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Chassis > ABS/VSC/TRAC > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
TRC(TRAC) OFF Indicator Light	Multi-information display (TRAC OFF message)	Display ON/OFF	Observe combination meter assembly
VSC OFF Indicator Light	VSC OFF indicator light	Indicator light ON/OFF	Observe combination meter assembly

Chassis > ABS/VSC/TRAC > Active Test

Tester Display
TRC(TRAC) OFF Indicator Light

Chassis > ABS/VSC/TRAC > Active Test

Tester Display
VSC OFF Indicator Light

(b) Check the multi-information display (TRAC OFF message) and VSC OFF indicator light on the combination meter assembly turns ON or OFF in accordance with the Techstream operation.

OK:

The multi-information display (TRAC OFF message) and VSC OFF indicator light turns ON or OFF in accordance with the Techstream operation.

NG

GO TO STEP 7

OK

5.	INSPECT INTEGRATION CONTROL AND PANEL ASSEMBLY

(a) Turn the power switch off.

(b) Remove the VSC OFF switch (integration control and panel assembly).

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(c) Inspect the VSC OFF switch (integration control and panel assembly).

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OK:

The VSC OFF switch (integration control and panel assembly) operates normally.

NG

REPLACE INTEGRATION CONTROL AND PANEL ASSEMBLY

OK

6.	CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - INTEGRATION CONTROL AND PANEL ASSEMBLY)

(a) Disconnect the A57 skid control ECU (brake booster with master cylinder assembly) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A57-8 (CSW) - I66-4 (+)	Always	Below 1 Ω
A57-8 (CSW) or I66-4 (+) - Body ground	Always	10 kΩ or higher
I66-1 (GND) - Body ground	Always	Below 1 Ω

HINT:

If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step.

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OK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.	INSPECT COMBINATION METER ASSEMBLY

(a) Turn the power switch off.

(b) Perform the Active Test of the combination meter assembly (meter CPU) using the Techstream.

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Body Electrical > Combination Meter > Active Test

Tester Display
Meter Display 1

Body Electrical > Combination Meter > Active Test

Tester Display
Indicat. VSC OFF

(c) Check the combination meter assembly.

OK:

The multi-information display and VSC OFF indicator light turns on or off in accordance with the Techstream operation.

OK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

NG

INSPECT METER / GAUGE SYSTEM

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