Code No.C1550 ECU internal error


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

OPERATION

  • Power is supplied to the electric power steering-ECU from the battery.

FUNCTION

  • The CAN bus signal from the torque sensor and resolver are sent to the electric power steering-ECU for motor control.

TROUBLE JUDGEMENT
Judgement Criterion
  • The system data is out of the prestored control range, and the microcomputer determines that there is an internal problem.
Fail Safe, Back Up Function
  • The electric power steering-ECU stops the motor control and illuminates the electric power steering warning display, then sets the diagnosis code No. C1550.

PROBABLE CAUSES

  • Malfunction of CAN bus line
  • Malfunction of the electric power steering-ECU

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 lines (Refer to GROUP 54C - Troubleshooting ). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis codes C1550 set?
Go to Step 3.
This diagnosis is complete.

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

Q. Is the diagnosis codes C1550 set?
Replace the electric power steering-ECU (Refer to ).Then go to Step 4.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

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

Q. Is the diagnosis codes C1550 set?
Return to Step 1.
This diagnosis is complete.