BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for HV Model): Brake Hold Standby Indicator Light Circuit; 2023 - 2025 MY Corolla Corolla HV [09/2022

Last Modified: 07-31-2024	6.11:8.1.0	Doc ID: RM1000000025DV2
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 Hold Standby Indicator Light Circuit; 2023 - 2025 MY Corolla Corolla HV [09/2022 - ]

Brake Hold Standby Indicator Light Circuit

DESCRIPTION

The brake hold standby indicator light turns on if brake hold control is possible when the following conditions required for operation standby are met and the brake hold switch (electric parking brake switch assembly) is pressed while the ignition switch is ON.

Conditions required for operation standby:
1. The driver door is closed.
2. The driver seat belt is fastened.
3. The system is normal.

WIRING DIAGRAM

PROCEDURE

PRE-CHECK

(a) If the brake hold standby indicator light does not illuminate even though the brake hold switch (electric parking brake switch assembly) is pushed, check that the brake hold function operation conditions are met.

The driver door is closed.
The driver seat belt is fastened.
The system is normal.

HINT:

If a malfunction occurs in one of the following systems, the brake hold operated indicator light will blink. If this occurs, perform troubleshooting on the malfunctioning system.

Electronically controlled brake system
Electric parking brake system
Hybrid control system

2.	READ VALUE USING GTS (BRAKE HOLD READY)

(a) Operate the GTS to read the Data List.

Chassis > Brake/EPB > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Brake Hold Ready

Brake hold control permission status

Not in stand-by mode / Stand-by mode

Not in stand-by mode: Brake hold function not operating (brake hold indicator not illuminated)

Stand-by mode: Brake hold function stand-by state (brake hold indicator illuminated)

Chassis > Brake/EPB > Data List

Tester Display
Brake Hold Ready

(b) Check the brake hold standby indicator light and mode condition on the GTS changes according to brake hold switch (electric parking brake switch assembly) operation.

Standard:

Brake Hold Switch (Electric Parking Brake Switch Assembly) Operation	Mode Condition Display	Brake Hold Standby Indicator Light
Not pressed	Not in stand-by mode	Does not come on
Pressing the brake hold switch (electric parking brake switch assembly)	Stand-by mode	Comes on

Result	Proceed to
Indicator light and mode condition display do not change	A
Mode condition display is normal, but indicator light does not change	B
Indicator light and mode condition display are normal	C

INSPECT METER / GAUGE SYSTEM

USE SIMULATION METHOD TO CHECK

3.	INSPECT ELECTRIC PARKING BRAKE SWITCH ASSEMBLY

(a) Turn the ignition switch off.

(b) Inspect the brake hold switch (electric parking brake switch assembly).

Click here

OK:

The brake hold switch (electric parking brake switch assembly) is normal.

REPLACE ELECTRIC PARKING BRAKE SWITCH ASSEMBLY

4.	CHECK HARNESS AND CONNECTOR (ELECTRIC PARKING BRAKE SWITCH ASSEMBLY - BRAKE ACTUATOR ASSEMBLY)

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

OK:

The connector is securely connected.

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

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

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
I159-10 (+B) - A51-44 (HZRI)	Always	Below 1 Ω
I159-10 (+B) or A51-44 (HZRI) - Body ground	Always	10 kΩ or higher
I159-12 (E) - Body ground	1 minute or more after disconnecting the cable from the negative (-) auxiliary battery terminal	Below 1 Ω

REPLACE BRAKE ACTUATOR ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR