Code No. C1278: Solenoid valve relay (open circuit)
Code No.C1279: Solenoid valve relay (short circuit)




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


ASTC-ECU receives the power supply to drive the incorporated solenoid valves at terminal 32. Each solenoid valve has a relay for driving. ASTC-ECU turns the relay of the solenoid valve to be driven ON or OFF to switch the hydraulic circuit.

DIAGNOSIS CODE SET CONDITIONS


These diagnosis code will be set under the cases below.
Code No. C1278
Code No. C1279

PROBABLE CAUSES


The most likely causes for these diagnosis codes to set are:

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.C1278 or C1279 set?

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.C1278 or C1279 set?

Replace the hydraulic unit assembly (integrated with ASTC-ECU). Then go to Step 4.

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 4. Check that the ABS warning lamp, brake warning lamp, ASTC indicator lamp and ASTC OFF indicator lamp are turned OFF.
Check that the ABS warning lamp, Brake warning lamp, ASTC indicator lamp and ASTC OFF indicator lamp goes out when the vehicle is driven at 10km/h or more.

Q. Does the ABS warning lamp, Brake warning lamp, ASTC indicator lamp and ASTC OFF indicator lamp go out?
Go to Step 5.
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 5. 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.C1278 or C1279 set?

Go to Step 1.

The procedure is complete.