Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: Brake System Control Module "A" System Voltage Line Internal Electronic Failure (C117A49,C137BA2)

Toyota Corolla Cross (2022-2025) Service Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System (for Gasoline Model) / Brake System Control Module "A" System Voltage Line Internal Electronic Failure (C117A49,C137BA2)

DESCRIPTION

If a malfunction is detected in the power supply circuit, the skid control ECU (brake actuator assembly) stores this DTC and the fail-safe function prohibits ABS operation.

This DTC is stored when the +BS terminal voltage meets one of the DTC detection conditions due to a malfunction in the power supply or charging circuit such as the auxiliary battery or alternator circuit, etc.

The DTC is cleared when the +BS terminal voltage returns to normal.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C117A49

Brake System Control Module "A" System Voltage Line Internal Electronic Failure

The vehicle speed is 15 km/h (9 mph) or more and the +BS terminal voltage is 9.6 V or more, the skid control ECU (brake actuator assembly) turns on more than one valve at the same time within a short period of time and the valve relay supply voltage drop exceeds the threshold.*
  • Battery
  • Charging system
  • Wire harness or connector
  • Internal power supply circuit of the skid control ECU (brake actuator assembly)

C137BA2

Brake System Control Module "A" System Voltage System Voltage Low

Any of the following is detected:

  1. The vehicle speed is 6 km/h (4 mph) or more and the +BS terminal voltage (soft low voltage) is less than 9.6 V for 1 second or more.
  2. The vehicle speed is 6 km/h (4 mph) or more and the +BS terminal voltage (hard low voltage) is less than 6.9 V for 1 second or more.
  3. The +BS terminal voltage is less than 6.7 V and the skid control ECU (brake actuator assembly) judges that power supply voltage is abnormal for 0.06 seconds or more.
  4. When the system has started, the +BS terminal voltage is less than 5 V for 0.5 seconds or more.
  5. The +BS terminal voltage is less than 2.6 V for 0.2 seconds or more.
  • Battery
  • Charging system
  • Wire harness or connector
  • Internal power supply circuit of the skid control ECU (brake actuator assembly)

*: The skid control ECU (brake actuator assembly) monitors the resistance of the power source line at the +BS terminal. A malfunction is detected when an abnormality occurs in the +BS terminal wire harness or its connection and the skid control ECU (brake actuator assembly) determines that the wiring resistance at the +BS terminal exceeds the standard resistance.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • Before performing troubleshooting, make sure to confirm that the auxiliary battery voltage is normal.

    Click here

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)

(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.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

(b) Disconnect the A151 skid control ECU (brake actuator 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

A151-30 (+BS) - Body ground

Always

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

2.

CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)

(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.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

(b) Disconnect the A151 skid control ECU (brake actuator 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

A151-1 (+BM) - Body ground

Always

11 to 14 V
OK

REPLACE BRAKE ACTUATOR ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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