Code No.C1225: Wheel Speed Sensor Malfunction (Abnormality in tyre size)


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table .).
  • Before replacing the ECU, ensure that the communication circuit is normal.

OPERATION



  • A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each wheel speed sensor.
  • The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the wheel speed sensor, and by the speed of rotation.
  • The wheel speed sensors transmit the frequency of the voltage pulses and the amount of voltage generated by each pulse to the ASTC-ECU.
  • The hydraulic unit assembly (integrated with ASTC-ECU) modulates the amount of braking force individually applied to each wheel cylinder.

DIAGNOSIS CODE SET CONDITION



PROBABLE CAUSES



  • Installation of different size tyres
  • Damaged wiring harness or connector
  • ASTC-ECU malfunction

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table .). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines
(1)Erase the diagnosis code.
(2)Drive the vehicle at 30 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 30 km/h or higher.

Q. Is the diagnosis code No.C1225 set?
Go to Step 3.
This diagnosis is complete.

STEP 3. Check the installation condition of the wheel and tyres.

Q. Is the check result normal?
Go to Step 4.
Install the correct size tyres. Then go to Step 5.

STEP 4. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 30 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 30 km/h or higher.

Q. Is the diagnosis code No.C1225 set?
Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to .). Then go to Step 5.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions .).

STEP 5. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 30 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 30 km/h or higher.

Q. Is the diagnosis code No.C1225 set?
Return to Step 1.
The procedure is complete.