Toyota Avalon (XX50) 2019-2022 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.

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• 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

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

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B

INSPECT CAN COMMUNICATION SYSTEM

A

(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

(a) Check the battery voltage.

Standard Voltage:

NG

CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY

OK

(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:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

OK

(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:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

OK

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

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

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

A

REPLACE BRAKE ACTUATOR ASSEMBLY

B

INSPECT METER / GAUGE SYSTEM