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-line diagnostic flow

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:

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)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). Then go to Step 3.

The procedure is complete.

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.