Toyota 4Runner: A-TRAC Indicator Light Remains ON

Toyota 4Runner Service Manual / Brake / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Hydraulic Brake Booster) / A-TRAC Indicator Light Remains ON

DESCRIPTION

This is the A-TRAC main switch circuit. When the A-TRAC switch is turned on with the transfer in L4, the A-TRAC function is available and the A-TRAC indicator light illuminates.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the master cylinder solenoid, perform calibration (See page ).

PROCEDURE

1.	CHECK CAN COMMUNICATION LINE

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Select CAN Bus Check from the System Selection Menu screen and follow the prompts on the screen to inspect the CAN bus (See page ).

OK:

CAN Bus Check indicates no malfunctions in CAN communication.

GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING)

2.	INSPECT TRACTION CONTROL SWITCH (A-TRAC SWITCH)

(a) Remove the A-TRAC switch (See page ).

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

Standard Resistance:

Tester Connection	Switch Condition	Specified Condition
8 (ATRC) - 5 (E)	Pushed in	Below 1 Ω
8 (ATRC) - 5 (E)	Not pushed in	10 kΩ or higher

Text in Illustration

*a	Component without harness connected (A-TRAC Switch)

REPLACE TRACTION CONTROL SWITCH (A-TRAC SWITCH)

3.	CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - A-TRAC SWITCH)

(a) Disconnect the A6 skid control ECU connector.

(b) Disconnect the U3 A-TRAC switch connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A6-13 (ATRC) - U3-8 (ATRC)	Always	Below 1 Ω
A6-13 (ATRC) - Body ground	Always	10 k Ω or higher
U3-5 (E) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	READ VALUE USING TECHSTREAM (A-TRAC INDICATOR LIGHT)

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

(f) Check the condition of the A-TRAC switch by operating the Techstream.

ABS/VSC/TRAC

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
A-TRAC Indicator Light	A-TRAC indicator light/ ON or OFF	ON: Indicator light on ON: Indicator light off	-

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

A-TRAC Indicator Light

A-TRAC indicator light/ ON or OFF

ON: Indicator light on

ON: Indicator light off

OK:

The Techstream displays ON or OFF according to A-TRAC switch operation.

GO TO METER / GAUGE SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING)

REPLACE MASTER CYLINDER SOLENOID

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