Code No.C1225: The difference diameter tyre

caution

If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Diagnose the CAN bus lines before the diagnosis codes (Refer to GROUP 54C, CAN bus-line diagnostic flow

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

The diagnosis code is set when ASTC-ECU judges that the difference of the average vehicle speed between the front wheel and rear wheel is 20 % or more at the vehicle speed of 20 km/h or more. This code may be set when driving has been made on the low mu road for a long time. It is necessary to confirm customer’s driving condition precisely.

PROBABLE CAUSES

The most likely causes for this diagnosis code to set are:

Installation of incorrect diameter tyres
Driving on the low mu road for a long time
Teeth lack or clogging of the ABS rotor
Damaged wiring harness or connector
Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)

DIAGNOSIS

STEP 1. M.U.T.-III CAN bus diagnostics

caution

Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.

(1)Connect M.U.T.-III to the 16-pin diagnosis connector.
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result normal?

Go to Step 3.

Repair the CAN bus line (Refer to GROUP 54C, CAN bus line Diagnostic flow

). Then go to Step 2.

STEP 2. Check whether the diagnosis code is reset.

caution

Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.

(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Drive the vehicle at 20 km/h or more for 5 seconds or more.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
(5)Turn the ignition switch to the "ON" position.
(6)Check if the diagnosis code is set.
(7)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.C1225 set?

Go to Step 3.

The procedure is complete.

STEP 3. Check the installed tyres.

Check if all the installed tyres are the same size.

Q. Is the check result normal?

	Go to Step 4.

	Install tires of the same size for all the wheels. Then go to Step 7.

STEP 4. Check the front hub for looseness.

note

If the wheel bearing is loose, the gap between the wheel speed sensor and ABS rotor may become excessive. Check the front hub, for looseness.

Check the front hub (Refer to GROUP 26, On-vehicle service - Wheel bearing axial play check ).

Q. Is the check result normal?

	Go to Step 5.

	NO (wheel bearing axial play is not within the standard value) : Replace the front hub assembly (Refer to GROUP 26, Front axle hub assembly ). Then go to Step 7.

	NO (wheel bearing axial play is not within the standard value) : Replace the rear axle shaft bearing (Refer to GROUP 27, Axle shaft assembly ). Then go to Step 7.

STEP 5. Check the ABS rotor.

Check the ABS rotor, for foreign material or deformation.

Q. Is the check result normal?

	Go to Step 6.

	NO (wheel bearing axial play is not within the standard value) : If the ABS rotor is contaminated with foreign material, clean it. If the front hub assembly is deformed, replace it (Refer to GROUP 26, Front axle hub assembly ). Then go to Step 7.

	NO (wheel bearing axial play is not within the standard value) : If the ABS rotor is contaminated with foreign material, clean it. If the rear axle shaft bearing is deformed, replace it (Refer to GROUP 27, Axle shaft assembly ). Then go to Step 7.

STEP 6. Check whether the diagnosis code is reset.

Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Drive the vehicle at 20 km/h or more for 5 seconds or more.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
(5)Turn the ignition switch to the "ON" position.
(6)Check if the diagnosis code is reset.
(7)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.C1225set?

Replace the hydraulic unit assembly (integrated with ASTC-ECU). Then go to Step 7.

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction

STEP 7. Check that the ABS warning lamp, ASTC indicator lamp, and ASTC OFF indicator lamp are turned OFF.

Check that the ABS warning lamp, ASTC indicator lamp and ASTC OFF indicator lamp goes out when the vehicle is driven at 20 km/h for 5 seconds or more.

Q. Does the ABS warning lamp, ASTC indicator lamp and ASTC OFF indicator lamp goes out?

	Go to Step 8.

	It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .

STEP 8. Check whether the diagnosis code is reset.

Q. Is code No.C1225 set?

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction

The procedure is complete.