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 When the diagnosis codes relating to the CAN communication error are output, make sure of the vehicle equipment. When the vehicle is not equipped with the system the engine-ECU communicates to, the diagnosis code is always output. This is not abnormal.

TROUBLE JUDGMENT


Check Condition
Judgment Criterion

COMMENT ON TROUBLE SYMPTOM


Current malfunction
Past malfunction

PROBABLE CAUSES




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 54D - 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 set?

Perform the troubleshooting of A/T-ECU (Refer to GROUP 23A - Troubleshooting <A/T> - Diagnosis Code chart ).
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. Combination meter

Q. Is the diagnosis code set?

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 set.

Q. Is the diagnosis code set?

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 set.

Q. Is the diagnosis code set?

Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, the vehicle equipped with the closed type DPF carries out the forcible DPF regeneration. (Refer to GROUP 17 - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ), 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 set?

Go to Step 1 .
The check is end.