Toyota Tacoma (2015-2018) Service Manual: A-TRAC Indicator Light Remains ON

Toyota Tacoma (2015-2018) Service Manual / 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 skid control ECU (master cylinder solenoid), perform calibration (See page ).
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.	CHECK CAN COMMUNICATION SYSTEM

(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: OK: ).

OK:

CAN Bus Check indicates no malfunctions in CAN communication.

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

2.	CHECK HARNESS AND CONNECTOR (ATRC TERMINAL)

(a) Disconnect the S1 skid control ECU (master cylinder solenoid) connector.

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

Standard Resistance:

Tester Connection	Switch Condition	Specified Condition
S1-13 (TRM3) - Body ground	A-TRAC switch not pushed in	10 kΩ or higher
S1-13 (TRM3) - Body ground	A-TRAC switch pushed in	Below 1 Ω

Text in Illustration

*a	Front view of wire harness connector (to Skid Control ECU (Master Cylinder Solenoid))

GO TO STEP 4

3.	READ VALUE USING TECHSTREAM (A-TRC(TRAC) SWITCH)

(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.

ABS/VSC/TRAC

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
A-TRC(TRAC) Switch	A-TRC Switch/ ON or OFF	ON: A-TRC switch on OFF: A-TRC switch off	-

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

A-TRC(TRAC) Switch

A-TRC Switch/ ON or OFF

ON: A-TRC switch on

OFF: A-TRC switch off

(f) Check that the mode display changes according to A-TRAC OFF switch operation.

OK:

Display changes according to switch operation.

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

REPLACE MASTER CYLINDER SOLENOID

4.	INSPECT 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
5 - 8	Switch is not pushed	Below 1 Ω
5 - 8	Switch is pushed	10 kΩ or higher

Text in Illustration

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

REPLACE A-TRAC SWITCH

5.	INSPECT ROOF CONSOLE BOX ASSEMBLY

(a) Remove the roof console box assembly.

for Double Cab: (See page )
for Access Cab: (See page )

Text in Illustration

Component without harness connected

(Roof Console Box Assembly)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R44-7 (ATRC) - 8	Always	Below 1 Ω
R44-12 (GND) - 5	Always	Below 1 Ω

Result

Result	Proceed to
OK	A
NG (for Double Cab)	B
NG (for Access Cab)	C

REPAIR OR REPLACE HARNESS OR CONNECTOR (MASTER CYLINDER SOLENOID - ROOF CONSOLE BOX ASSEMBLY)

REPLACE ROOF CONSOLE BOX ASSEMBLY

A-TRAC Indicator Light does not Come ON

DESCRIPTION The A-TRAC does not operate even if the A-TRAC switch is pressed under the following conditions: The TRAC or VSC system is faulty. The temperature inside the hydraulic brake ...

VSC Buzzer Circuit

DESCRIPTION The skid control ECU (master cylinder solenoid) is connected to the combination meter via CAN communication. The combination meter has a built-in VSC warning buzzer: Sounds int ...

Other materials:

Headlight Dimmer Switch Circuit
DESCRIPTION The main body ECU (multiplex network body ECU) receives the following switch information: Light control switch position is off (DRL OFF), tail, head or AUTO (DRL). Dimmer switch position is high, low or high flash (pass). Front fog light switch position is on or off ...

Terminals Of Ecu
TERMINALS OF ECU 1. CHECK SLIDING ROOF ECU (SLIDING ROOF DRIVE GEAR SUB-ASSEMBLY) (a) Disconnect the S50 sliding roof ECU (sliding roof drive gear sub-assembly) connector. (b) Measure the resistance and voltage according to the value(s) in the table below. HINT: Measure the values on the ...

Problem Symptoms Table
PROBLEM SYMPTOMS TABLE NOTICE: Before replacing the ECM, refer to Registration. w/o Smart Key System: Click here w/ Smart Key System: Click here When the millimeter wave radar sensor assembly is replaced with a new one, adjustment of the radar sensor beam axis must be ...