Code No. C1078: Tyre with incorrect diameter equipped


caution If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, always diagnose the CAN bus lines.

OPERATION



DIAGNOSIS CODE SET CONDITIONS




  • Drive mode-selector: 4WD
  • Difference in rotation speed between the front and rear wheels exceeds continuously a specific value.

PROBABLE CAUSES


Current trouble
  • Tyre with incorrect diameter (high-pressure type spare tyre or flat tyre) equipped
  • Improper adjusted tyre pressure
Past trouble
  • Tyre with incorrect diameter (high-pressure type spare tyre or flat tyre) has been installed.
  • The tyre pressure has been adjusted due to improper tyre pressure.

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
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 line (Refer to GROUP 54C - Troubleshooting/CAN Bus Diagnostics Table ). On completion, go to Step 2.

STEP 2. Check whether the diagnosis code is reset after repairing the CAN bus line.
(1)Erase the diagnosis code.
(2)Drive the vehicle straight with throttle opening angle of approximately 50% or less, and constant vehicle speed of 30 km/h or higher for 20 seconds or longer.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code No. C1078 set?
Go to Step 3.
This diagnosis is complete.

STEP 3. Tyre check

Q. Are all installed wheels and tyres same in size?
Go to Step 4.
Install the same size wheels and tyres. Then go to Step 4.

STEP 4. Tyre pressure check
Check that the tyre pressure of the installed tyres agrees with the tyre pressure specified on the tyre pressure label.

Q. Is the tyre pressure normal?
Go to Step 6.
Adjust the tyre pressure. Then go to Step 5.

STEP 5. Check whether the diagnosis code is reset.
Drive the vehicle straight with throttle opening angle of approximately 50% or less, and constant vehicle speed of 30 km/h or higher for 20 seconds or longer.

Q. Is the diagnosis code No. C1078 set?
Go to Step 6.
This code is set because the tyre pressure was improper or a tyre with incorrect diameter is installed.

STEP 6. M.U.T.-III data list
Check the following data list (Refer to ).

  • Item 16: FL wheel speed sensor
  • Item 17: FR wheel speed sensor
  • Item 18: RL wheel speed sensor
  • Item 19: RR wheel speed sensor

Q. Is the check result normal?
Go to Step 7.
Troubleshoot the ABS system (Refer to GROUP 35B - Troubleshooting/Diagnosis Code Chart <Vehicles with ABS>), the ASC system (Refer to GROUP 35C - Troubleshooting/Diagnosis Code Chart <Vehicles with ASC>). Then go to Step 7.

STEP 7. Check whether the diagnosis code is reset.
Drive the vehicle straight with throttle opening angle of approximately 50% or less, and constant vehicle speed of 30 km/h or higher for 20 seconds or longer.

Q. Is the diagnosis code No. C1078 set?
Replace 4WD-ECU(Refer to ). Then go to Step 8 .
This diagnosis is complete.

STEP 8. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. C1078 set?
Diagnose again from Step 1.
This diagnosis is complete.