Toyota Tacoma (2015-2018) Service Manual: ABS Warning Light Remains ON

Toyota Tacoma (2015-2018) Service Manual / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Vacuum Brake Booster) / ABS Warning Light Remains ON

DESCRIPTION

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

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

The skid control ECU (brake actuator assembly) connectors are disconnected from the skid control ECU (brake actuator assembly).
There is a malfunction in the skid control ECU (brake actuator assembly) internal circuit.
There is an open in the harness between the combination meter assembly and the skid control ECU (brake actuator assembly).
The ABS control system is defective.
w/ Rear Differential Lock:
The rear differential is locked.

HINT:

In some cases, the Techstream cannot be used when the skid control ECU (brake actuator assembly) is abnormal.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information (See page ).
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.	CHECK CAN COMMUNICATION SYSTEM

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

Result

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

CHECK CAN COMMUNICATION SYSTEM

2.	CHECK IF BRAKE ACTUATOR ASSEMBLY CONNECTOR IS SECURELY CONNECTED

(a) Check if the skid control ECU (brake actuator assembly) connector is securely connected.

OK:

The connector is securely connected.

CONNECT CONNECTOR TO BRAKE ACTUATOR ASSEMBLY CORRECTLY

3.	INSPECT BATTERY

(a) Check the battery voltage.

Standard voltage:

11 to 14 V

CHECK OR REPLACE CHARGING SYSTEM OR BATTERY

4.	CHECK TERMINAL VOLTAGE (IG1 TERMINAL)

(a) Disconnect the S1 skid control ECU (brake actuator assembly) connector.

(b) Turn the ignition switch to ON.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
S1-12 (IG1) - Body ground	Ignition switch ON	11 to 14 V

Text in Illustration

*a	Front view of wire harness connector (to Skid Control ECU [Brake Actuator Assembly])

REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

5.	CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

(a) Turn the ignition switch off.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
S1-25 (GND1) - Body ground	Always	Below 1 Ω

Text in Illustration

*a	Front view of wire harness connector (to Skid Control ECU [Brake Actuator Assembly])

Result

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

GO TO STEP 7

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

6.	CHECK FOR DIFFERENTIAL SYSTEM

(a) Reconnect the S1 skid control ECU (brake actuator assembly) connector.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Enter the following menus: Powertrain / Four Wheel Drive / Trouble Codes.

(f) Check for DTCs.

Result

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

GO TO DIFFERENTIAL SYSTEM (DIAGNOSTIC TROUBLE CODE CHART)

7.	READ VALUE USING TECHSTREAM (ABS WARNING LIGHT)

(a) Reconnect the S1 skid control ECU (brake actuator assembly) connector.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

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

(f) According to the display on the Techstream, read the Data List.

ABS/VSC/TRAC

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

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

ABS Warning Light

ABS warning light

OFF or ON

OFF: Warning light off

ON: Warning light on

(g) Check the Techstream display condition of the ABS warning light.

Result

Result	Proceed to
Display of the Data List remains OFF	A
Display of the Data List remains ON	B

INSPECT METER / GAUGE SYSTEM

REPLACE BRAKE ACTUATOR ASSEMBLY

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