Code No. U1101: A/T-ECU Time-out <A/T>


caution If Diagnosis Code U1101 is output from engine-ECU surely perform CAN busline diagnosis.
caution Replace ECU after certainly confirming that the communication circuits are normal.
note The diagnosis code is always output because the M/T vehicle is not equipped with the A/T-ECU, which is not abnormal.

TROUBLE JUDGMENT


Check Conditions
  • The diagnosis code setting enabled signal is received from ETACS-ECU.
Judgment Criterion
  • The signals cannot be received from A/T-ECU for 65 second or more.

COMMENT ON TROUBLE SYMPTOM


Current malfunction
  • The failure is possibly caused by malfunction of the harness and connector in CAN busline between engine-ECU and A/T-ECU, by malfunction in the power supply system of A/T-ECU, in combination meter itself, in engine-ECU.
Past malfunction
  • Focus on diagnosing malfunction of the harness and connector in CAN busline between engine-ECU and A/T-ECU as well as malfunction in the power supply system of A/T-ECU. Refer to past trouble (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Treat Past Trouble ) for the diagnosis procedure.
    note In case of Past trouble, M.U.T.-III CAN bus diagnosis cannot detect the failure even if there is malfunction in CAN bus, so that check CAN busline in the same way as Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ). The diagnosis codes being output to each ECU with CAN communication can narrow down the most suspected area (Refer to GROUP 54C - Can Bus Diagnosis Table ).

PROBABLE CAUSES



  • Failed of the harness and the connector
  • Failed A/T-ECU
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

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

  • Using M.U.T.-III, perform CAN busline diagnosis.

Q. Is the check result normal?
Go to Step 2 .
Correct CAN busline (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnosis Table ), and then go to Step 6 .

STEP 2. M.U.T.-III other system diagnosis codes.

  • Confirm whether the diagnosis codes are output from A/T-ECU.

Q. Is the diagnosis code output?
Perform the troubleshooting of A/T-ECU (Refer to GROUP 23A - Check Chart for Diagnosis Code ).
NO : Go to Step 3 .

STEP 3. M.U.T.-III other system diagnosis codes.

  • Confirm whether Diagnosis Code U1101: A/T-ECU time out is output from the following ECU having CAN communication with automatic transmission.

  1. ETACS-ECU

Q. Is the diagnosis code output?
Go to Step 4 .
Go to Step 5 .

STEP 4. Reconfirmation of diagnosis codes

  • Reconfirm whether the diagnosis codes are output from engine-ECU

  1. Erase the diagnosis codes being output.
  2. Ignition switch: "LOCK" (OFF) to ON
  3. Confirm whether the diagnosis codes are output.

Q. Is the diagnosis code output?
After replacing the A/T-ECU, go to Step 6 .
Intermittent malfunction in CAN busline between engine-ECU and A/T-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 5. Reconfirmation of diagnosis codes

  • Reconfirm whether the diagnosis codes are output from engine-ECU

  1. Erase the diagnosis codes being output.
  2. Ignition switch: "LOCK" (OFF) to ON
  3. Confirm whether the diagnosis codes are output.

Q. Is the diagnosis code output?
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and lean fuel injection (Refer to GROUP 00 - Precautions Before Service - What The common Rail Engine Learns ), and then go to Step 6 .
Intermittent malfunction in CAN busline between engine-ECU and A/T-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Reconfirmation of diagnosis codes

  • Reconfirm whether the diagnosis codes are output from engine-ECU

  1. Erase the diagnosis codes being output.
  2. Ignition switch: "LOCK" (OFF) to ON
  3. Confirm whether the diagnosis codes are output.

Q. Is the diagnosis code output?
Go to Step 1 .
The check is end.