Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: Electronic Brake Booster Control Module "A" Backup Power Supply Voltage System Voltage Low (C125DA2,C125DA3)

Toyota Corolla Cross (2022-2024) Service Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System (for Hev Model) / Electronic Brake Booster Control Module "A" Backup Power Supply Voltage System Voltage Low (C125DA2,C125DA3)

DESCRIPTION

The brake control power supply assembly is used as an auxiliary power supply for brake control when the voltage of the auxiliary battery is low.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

DTC Output from

Note

C125DA2

Electronic Brake Booster Control Module "A" Backup Power Supply Voltage System Voltage Low

Voltage from brake control power supply assembly is less than 2.8 V for 10 seconds.

  • Wire harness or connector
  • Electric brake booster (brake booster with master cylinder assembly)

Does not come on

Brake Booster

Output ECU: Electric brake booster (brake booster with master cylinder assembly)

C125DA3

Electronic Brake Booster Control Module "A" Backup Power Supply Voltage System Voltage High

Brake control power supply assembly power source voltage is abnormal for 10 seconds or more.

  • Wire harness or connector
  • Electric brake booster (brake booster with master cylinder assembly)

Does not come on

Brake Booster

Output ECU: Electric brake booster (brake booster with master cylinder assembly)

WIRING DIAGRAM

Refer to DTC C121F87.

Click here

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (+BC TERMINAL)

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

OK:

The connector is securely connected.

*a

Front view of wire harness connector

(to Brake Control Power Supply Assembly)

(b) Disconnect the O223 brake control power supply assembly connector.

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

OK:

No deformation or corrosion.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

O223-1 (+BC) - Body ground

Always

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

2.

CHECK HARNESS AND CONNECTOR (GND TERMINAL)

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

OK:

The connector is securely connected.

(b) Disconnect the O223 brake control power supply assembly connector.

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

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

O223-4 (GND) - Body ground

1 minute or more after disconnecting the cable from the negative (-) auxiliary battery terminal

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.

CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE CONTROL POWER SUPPLY ASSEMBLY)

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

OK:

The connector is securely connected.

(b) Disconnect the A189 electric brake booster (brake booster with master cylinder assembly) connector.

(c) Disconnect the O223 brake control power supply assembly connector.

(d) Check both the connector case and the terminals 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

A189-1 (CBKP) - O223-6 (OUT)

Always

Below 1 Ω

A189-1 (CBKP) or O223-6 (OUT) - Body ground and other terminals

Always

10 kΩ or higher

OK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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