Toyota Avalon Service & Repair Manual: 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) connector is 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 and skid control ECU (brake actuator assembly).
  • The ABS is defective.

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 system variant learning and acceleration sensor zero point calibration.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • Before performing this procedure, depress the brake pedal and confirm that the stop lights illuminate.

PROCEDURE

1.

CHECK CAN COMMUNICATION SYSTEM

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

Click here

Result

Proceed to

DTCs are not output

A

DTCs are output

B

B

INSPECT CAN COMMUNICATION SYSTEM

A

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.

NG

CONNECT CONNECTOR TO BRAKE ACTUATOR ASSEMBLY CORRECTLY

OK

3.

CHECK BATTERY

(a) Check the battery voltage.

Standard Voltage:

Tester Connection

Condition

Specified Condition

Positive (+) terminal - Negative (-) terminal

Engine switch off

11 to 14 V

NG

CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY

OK

4.

CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)

(a) Turn the engine switch off.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

(b) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

(c) Disconnect the A28 skid control ECU (brake actuator assembly) connector.

(d) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A28-30 (+BS) - Body ground

Always

11 to 14 V

A28-36 (IG1) - Body ground

Engine switch on (IG)

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

OK

5.

CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

(a) Turn the engine switch off.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A28-46 (GND1) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

OK

6.

READ VALUE USING TECHSTREAM (ABS WARNING LIGHT)

(a) Reconnect the A28 skid control ECU (brake actuator assembly) connector.

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

Chassis > ABS/VSC/TRAC/EPB > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

ABS Warning Light

ABS warning light

ON or OFF

ON: Warning light on

OFF: Warning light off

-

Chassis > ABS/VSC/TRAC/EPB > Data List

Tester Display

ABS Warning Light

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

Result

Proceed to

The value of ABS Warning Light is ON

A

The value of ABS Warning Light is OFF

B

A

REPLACE BRAKE ACTUATOR ASSEMBLY

B

INSPECT METER / GAUGE SYSTEM

    ABS Warning Light does not Come ON

    Brake Actuator Operation Sound is Loud during Initial Check

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