Code No.C1225:
Wheel Speed Sensor Malfunction (Abnormality in tyre size)
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- 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
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- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit (integrated with ASTC-ECU) is replaced, always carry out
the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to ).
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OPERATION
- A toothed rotor (for wheel speed detection) generates
a voltage pulse as it moves across the pickup field of each wheel speed sensor.
- The wheel speed sensor transmit the frequency of the pulses 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
This diagnosis code is set when the average speed of the front wheels differs from that
of the rear wheel by 20 % or more after the vehicle speed exceeds 30 km/h.
PROBABLE CAUSES
- Installation of different size tyres
- Damaged wiring harness or connector
- Malfunction of ydraulic unit assembly (integrated with ASTC-ECU)
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STEP 1. M.U.T.-III CAN bus diagnosis
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Use M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step 3.
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 Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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(1)Turn the ignition switch to the "ON" position.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(3)Drive the vehicle at 30 km/h or more.
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The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 30 km/h
or higher.
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(4)Erase the diagnosis code.
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Q.
Is diagnosis code No.C1225 set?
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Go to Step 3.
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This diagnosis is complete.
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STEP 3. Check the installation condition of the wheel and tyres.
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Q.
Is the check result normal?
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Go to Step 4.
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Install the correct size tyres. Then go to Step 5.
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STEP 4. Check whether the diagnosis code is set again.
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(1)Turn the ignition switch to the "ON" position.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(3)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.
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(4)Erase the diagnosis code.
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Q.
Is diagnosis code No.C1225 set?
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Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to ).
Then go to Step 5.
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunctions ).
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STEP 5. Check whether the diagnosis code is set again.
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(1)Turn the ignition switch to the "ON" position.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(3)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.
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(4)Erase the diagnosis code.
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Q.
Is diagnosis code No.C1225 set?
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Return to Step 1.
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The procedure is complete.
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