Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000002MO1F
Model Year Start: 2023 Model: Corolla Prod Date Range: [09/2022 -           ]
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for HV Model): Brake Warning Light Remains ON; 2023 - 2025 MY Corolla Corolla HV [09/2022 -        ]

Brake Warning Light Remains ON

DESCRIPTION

This procedure is for troubleshooting when the brake system warning light (red indicator) remains on but no DTCs are output.

The skid control ECU (brake actuator assembly) controls the brake system warning light (red indicator) in the combination meter assembly via CAN communication.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Before performing this procedure, depress the brake pedal and confirm that the stop lights illuminate.

PROCEDURE

1.

PRE-CHECK

(a) Check that all of the following conditions required for the brake system warning light (red indicator) to turn off are met:

(1) The brake fluid level in the brake master cylinder reservoir assembly is not low.

NEXT

2.

INSPECT BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY

(a) With a sufficient level of brake fluid, disconnect the A125 brake fluid level warning switch (brake master cylinder reservoir assembly) connector and confirm that the brake system warning light (red indicator) turns off.

OK:

The brake system warning light (red indicator) turns off.

HINT:

If the brake system warning light (red indicator) turns off, there is a short in the brake fluid level warning switch (brake master cylinder reservoir assembly) circuit.

OK

REPLACE BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY

NG

3.

CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY)

(a) Disconnect the A51 skid control ECU (brake actuator assembly) connector.

(b) Disconnect the A125 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A51-4 (LBL) or A125-1 (+) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

INSPECT COMBINATION METER ASSEMBLY

(a) Perform the Active Test of the combination meter assembly using the GTS.

Body Electrical > Combination Meter > Active Test

Tester Display

Brake Warning

(b) Check the combination meter assembly.

OK:

The brake system warning light (red indicator) turns on or off in accordance with GTS operation.

OK

REPLACE BRAKE ACTUATOR ASSEMBLY

NG

INSPECT METER / GAUGE SYSTEM 2023 MY Corolla Corolla Hatchback Corolla HV GR Corolla [09/2022 - 11/2022]; METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM (except 12.3 Inch Display): HOW TO PROCEED WITH TROUBLESHOOTING 2023 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [11/2022 -        ]; METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM (except 12.3 Inch Display): HOW TO PROCEED WITH TROUBLESHOOTING