Code No. U0100: Engine-ECU Time-out


caution
  • If diagnosis code U0100 is set in the A/T-ECU, always diagnose the CAN main bus line.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.

DIAGNOSIS CODE SET CONDITIONS


If signals from the engine-ECU transmitted via CAN bus line cannot be received, code No.U0100 is set.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis

  • Use M.U.T.-III to perform CAN bus line diagnosis.

Q. Is the check result normal?
Go to Step 2.
Repair CAN bus line (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnostics Table ).

STEP 2. Use M.U.T.-III to confirm a diagnosis code of other systems.
Check that the other ECU performing CAN communication with engine-ECU sets diagnosis code No.U0100, No.U1100.

Q. Is diagnosis code set?
Go to Step 3.
Go to Step 4.

STEP 3. Check whether the diagnosis code is set again.

  1. Erase the set diagnosis code.
  2. Ignition switch: "LOCK" (OFF) → "ON"
  3. Confirm whether the diagnosis code is set.

Q. Is diagnosis code No.U0100 set?
Replace the engine-ECU.
Intermittent malfunction in CAN bus line between A/T-ECU and engine-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 4. Check whether the diagnosis code is set again.

  1. Erase the set diagnosis code.
  2. Ignition switch: "LOCK" (OFF) → "ON"
  3. Confirm whether the diagnosis code is set.

Q. Is diagnosis code No.U0100 set?
Replace the A/T-ECU.
Intermittent malfunction in CAN bus line between A/T-ECU and engine-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).