Code No.C1226:
Control solenoid valve (FR) pressure holding system
Code No.C1236: Control solenoid
valve (FL) pressure holding system
Code No.C1246: Control solenoid valve (RR) pressure
holding system
Code No.C1256: Control solenoid valve (RL) pressure holding system
Code
No.C1231: Control solenoid valve (FR) decompressing system
Code No.C1241: Control solenoid
valve (FL) pressure reducing system
Code No.C1251: Control solenoid valve (RR) pressure
reducing system
Code No.C1261: Control solenoid valve (RL) decompressing system
Code
No.C1300: Linear valve (secondly)
Code No.C1310: Linear valve (primary)
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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
- The ASTC-ECU contains the power supply circuit for the solenoid valve. The
solenoid valve is energised by the valve relay, which is incorporated in the ASTC-ECU.
- The valve relay, which is incorporated in the ASTC-ECU, is always energising the
solenoid valve unless the initial check is in progress when the ignition switch is turned on.
- The ASTC-ECU activates the solenoid valve by turning on its driving transistor.
DIAGNOSIS CODE SET CONDITIONS
These diagnosis codes will be set under the cases below.
Code No.C1226, C1231, C1236, C1241, C1246, C1251, C1256, C1261
- The output of the each solenoid valve does not change when the solenoid valve is
"ON" and the solenoid valve monitor is "ON"
Code No.C1300, C1310
- The linear valve monitor is "OFF" when the linear valve has an open circuit.
- The linear valve monitor is "OFF" when the linear valve is "ON"
PROBABLE CAUSES
- Malfunction of the hydraulic 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. 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)Erase the diagnosis code.
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(3)Turn the ignition switch to the "LOCK" (OFF) position.
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(4)Turn the ignition switch to the "ON" position.
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(5)Check if the diagnosis code is set.
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(6)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is code No.C1226, C1231, C1236, C1241, C1246, C1251, C1256, C1261, C1300 or C1310
set?
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Replace the hydraulic unit (integrated with ASTC-ECU) (Refer to ). Then
go to Step 3.
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Intermittent malfunction (Refer to GROUP 00 -
How to Cope with Intermittent
Malfunctions ).
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STEP 3. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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(1)Turn the ignition switch to the "ON" position.
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(2)Erase the diagnosis code.
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(3)Turn the ignition switch to the "LOCK" (OFF) position.
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(4)Turn the ignition switch to the "ON" position.
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(5)Check if the diagnosis code is set.
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(6)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is code No.C1226, C1231, C1236, C1241, C1246, C1251, C1256, C1261, C1300 or C1310
set?
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Return to Step 1.
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The procedure is complete.
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