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)


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 Diagnostics Table ).

OPERATION

  • The ASTC-ECU contains the power supply circuit for the solenoid valve. The solenoid valve is energized by the valve relay, which is incorporated in the ASTC-ECU.
  • The valve relay, which is incorporated in the ASTC-ECU, is always energizing 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
The most likely causes for these diagnosis codes to set are:

  • Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)

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. Check whether the diagnosis code is reset.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.C1226, C1231, C1236, C1241, C1246, C1251, C1256, C1261, C1300 or C1310 set?
Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to ). Then go to Step 3.
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 3. 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)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.C1226, C1231, C1236, C1241, C1246, C1251, C1256, C1261, C1300 or C1310 set?
Go to Step 1.
The procedure is complete.