Toyota 4Runner: ABS Warning Light Remains ON

Toyota 4Runner Service Manual / Brake / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Hydraulic Brake Booster) / ABS Warning Light Remains ON

DESCRIPTION

If any of the following is detected, the ABS warning light remains on.

The skid control ECU connectors are disconnected from the skid control ECU.
There is a malfunction in the skid control ECU internal circuit.
There is an open in the harness between the combination meter and skid control ECU.
The anti-lock brake system is defective.
The voltage at terminal IG1 is high.
The rear differential is locked.*

*: w/ Rear Differential Lock

HINT:

It may not be possible to use the Techstream when the skid control ECU is abnormal.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the 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 THAT SKID CONTROL ECU CONNECTOR IS SECURELY CONNECTED

(a) Check the skid control ECU connector connection.

OK:

The connector is securely connected.

CONNECT CONNECTOR TO ECU CORRECTLY

2.	CHECK FOR DTC

(a) Check for DTCs (See page ).

Result

Result	Proceed to
DTC is not output	A
DTC is output	B

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

3.	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)

4.	READ VALUE USING TECHSTREAM (IG1 VOLTAGE VALUE)

GO TO STEP 7

5.	CHECK TERMINAL VOLTAGE (EXI3)

(a) Disconnect the A6 skid control ECU connector.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

A6-40 (EXI3) - Body ground

Ignition switch ON

w/ Rear Differential Lock: Rear differential free

11 to 14 V

Text in Illustration

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

Result

Result	Proceed to
OK	A
NG (for 4WD)	B
NG (for 2WD)	C

GO TO STEP 9

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.	READ VALUE USING TECHSTREAM (ABS WARNING 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.

ABS/VSC/TRAC

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
ABS Warning Light	ABS warning light/ ON or OFF	OFF	-

(f) When performing the ABS Warning Light Active Test, check ABS Warning Light in the Data List (See page ).

ABS/VSC/TRAC

Tester Display	Test Part	Control Range	Diagnostic Note
ABS Warning Light	ABS warning light	Warning light ON/OFF	Observe the combination meter.

Result

Result		Proceed to
Data List Display	Data List Display when Performing Active Test ON/OFF Operation	Proceed to
ON	Does not change between ON and OFF	A
ON	Changes between ON and OFF	B
OFF	Does not change between ON and OFF	A
OFF	Changes between ON and OFF	B

REPLACE MASTER CYLINDER SOLENOID

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

7.	CHECK TERMINAL VOLTAGE (IG1)

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.	CHECK HARNESS AND CONNECTOR (GND1, GND2 AND GND3 TERMINAL)

REPLACE MASTER CYLINDER SOLENOID

REPAIR OR REPLACE HARNESS OR CONNECTOR

9.	CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU EXI3 CIRCUIT)

(a) Disconnect the A6 skid control ECU connector.

(b) Disconnect the F47 four wheel drive control ECU connector.

Disconnect the D3 rear differential lock detection switch connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A6-40 (EXI3) - Body ground	Always	10 kΩ or higher

Result

Result	Proceed to
OK (w/o Rear Differential Lock)	A
OK (w/ Rear Differential Lock)	B
NG	C

GO TO STEP 11

REPAIR OR REPLACE HARNESS OR CONNECTOR

10.	CHECK TERMINAL VOLTAGE (EXI3)

(a) Disconnect the A6 skid control ECU connector.

(b) Connect the F47 four wheel drive control ECU connector.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A6-40 (EXI3) - Body ground	Ignition switch ON	11 to 14 V

Text in Illustration

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

REPLACE MASTER CYLINDER SOLENOID

REPLACE FOUR WHEEL DRIVE CONTROL ECU

11.	INSPECT REAR DIFFERENTIAL LOCK DETECTION SWITCH (REAR DIFFERENTIAL LOCK POSITION SWITCH)

(a) Remove the rear differential lock detection switch (See page ).

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

Standard Resistance:

Tester Connection	Switch Condition	Specified Condition
2 (+B) - 1 (GND)	Pushed in	Below 1 Ω
2 (+B) - 1 (GND)	Not pushed in	10 kΩ or higher

Text in Illustration

*a	Component without harness connected (Differential Lock Detection Switch (Differential Lock Position Switch))

REPLACE REAR DIFFERENTIAL LOCK DETECTION SWITCH (REAR DIFFERENTIAL LOCK POSITION SWITCH)

12.	INSPECT TERMINAL VOLTAGE (EXI3)

(a) Disconnect the A6 skid control ECU connector.

(b) Connect the F47 four wheel drive control ECU connector.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A6-40 (EXI3) - Body ground	Ignition switch ON	11 to 14 V

Text in Illustration

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

REPLACE MASTER CYLINDER SOLENOID

REPLACE FOUR WHEEL DRIVE CONTROL ECU

Control Module Communication Bus OFF (U0073,U0100,U0114,U0123,U0124,U0126)

DESCRIPTION DTC Code DTC Detection Conditions Trouble Area U0073 One of the following conditions is met: When the IG1 termin ...

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DESCRIPTION Refer to ABS Warning Light Remains ON (See page ). WIRING DIAGRAM Refer to ABS Warning Light Remains ON (See page ). CAUTION / NOTICE / HINT NOTICE: When replacing the master cyl ...

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