Wheels lock when braking

1. Wheels lock when braking description of symptom

The wheels lock when braking.

2. Wheels lock when braking diagnostics

1. Preliminary inspection

Perform the brake control system inspection.

Refer to "54.Brake Control 4A.Troubleshooting(ABS/ESC) diagnostic System Check - Brake Controls".

Inspect for the following.

  • There should be no malfunctions in the warning light and indicator light operation.
  • There should be no DTC input.

2. Visual inspection

Visually inspect the vehicle condition with the following in mind before installing, removing, disassembling, and inspecting the components.

  • Terminal connection status inspection
  • Inspection for aftermarket accessory power diverged from the EHCU
  • EHCU ground installation status inspection
  • Installation status inspection of the pipes and hoses in the brake system

3. Diagnostics

1) ABS operation check

Perform a test drive and activate the ABS.

Go to Ground circuit inspection if the ABS does not activate.

If the vehicle speed during ABS operation is 10 km/h {6.2 mph} or less, go to Wheel speed sensor circuit inspection.

2) Wheel speed sensor circuit inspection

Refer to DTCs C0031[01] - C003A[2F], and inspect the wheel speed sensor circuit.

If the inspection results are normal, go to Ground circuit inspection.

If the inspection results are abnormal, repair the wheel speed sensor. After completing the procedure, go to Repair verification.

3) Ground circuit inspection

Inspect for an open circuit, high resistance, or terminal connection status in the ground circuit of the EHCU and motor.

If the inspection results are normal, go to EHCU replacement.

If the inspection results are abnormal, repair the applicable areas. After completing the procedure, go to Repair verification.

4) EHCU replacement

Note

  • Perform programming after replacing the EHCU.

Refer to "4.Brakes 4Z.Brake Electrical Control EHCU removal".

Refer to "4.Brakes 4Z.Brake Electrical Control EHCU installation".

Refer to "4.Brakes 4Z.Brake Electrical Control EHCU setting".

After completing the procedure, go to Repair verification.

5) Repair verification

Check whether all the components are properly installed.

Perform a test drive and check the symptoms.