C1078

DTC C1078: Tire Turning Malfunction

CAUTION
^ If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION
AWC-ECU receives the wheel speed data from ASC-ECU via the CAN communication.

DTC SET CONDITIONS
The wheel speed is observed when the steering angle is in the neutral position, and the code is set when the wheel speed, which is more than the specified value, is detected.

PROBABLE CAUSES
^ Tire with incorrect diameter equipped
^ Improper tire pressure
^ Malfunction of ASC-ECU
^ Malfunction of AWC-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus line. After repairing the CAN bus line, go to Step 2.

STEP 2. Check whether the DTC is reset.
Q: Is DTC No. C1078 set?
YES: Go to Step 3.
NO: This diagnosis is complete.

STEP 3. Check the tires
Check that the wheels/tires with the identical size are installed, and that each tire pressure is within the value specified on the tire pressure label.
Q: Is the check result normal?
YES: Go to Step 4.
NO: Install the wheels/tires with the identical size, or adjust the tire pressure. Then go to Step 5.

STEP 4. Scan tool diagnostic trouble code
Check the ASC diagnostic trouble code. Diagnostic Trouble Code Descriptions
Q: Is the DTC set?
YES: Perform the relevant troubleshooting.
NO: Go to Step 5.

STEP 5. Scan tool service data
Check the following service data. (Data List Reference Table)
^ Item No.22: FL wheel speed sensor [FL]
^ Item No.23: FL wheel speed sensor [FR]
^ Item No.24: FL wheel speed sensor [RL]
^ Item No.25: FL wheel speed sensor [RR]
Q: Is the check result normal?
YES: Intermittent malfunction.
NO: Replace the AWC-ECU.