Code No.U1101 Engine-A/T-ECU <A/T> Time-out (Related to Automatic Transmission)


caution If diagnosis code U1100 or U1101 is set in the combination meter, always diagnose the CAN bus lines.
caution Whenever the ECU is replaced, ensure that the communication circuit is normal.

TROUBLE JUDGMENT
The combination meter receives transmission control system-related signal from the engine-A/T-ECU <A/T> via CAN bus lines. If the display unit can not receive the necessary signals, diagnosis code U1101 will be set.
note For M/T-vehicles, diagnosis code No.U1101 does not mean that there is a problem.

COMMENTS ON TROUBLE SYMPTOM
Current trouble
  • Connector(s) or wiring harness in the CAN bus lines between the engine-A/T-ECU <A/T> and the combination meter, the power supply system to the engine-A/T-ECU <A/T>, the engine-ECU or engine-A/T-ECU <A/T> itself, or the combination meter may be defective.
Past trouble
  • Carry out diagnosis with particular emphasis on connector(s) or wiring harness in the CAN bus lines between the engine-A/T-ECU <A/T> and the combination meter, and the power supply system to the engine-A/T-ECU <A/T>. For diagnosis procedures, refer to "How to cope with past trouble" (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points ).
    note For a past trouble, you may not find it by the M.U.T.-III CAN bus diagnostics even if there is any failure in CAN bus lines. In this case, refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ). and check the CAN bus lines. You can narrow down the possible cause of the trouble by referring to the diagnosis code, which is set regarding the CAN communication-linked ECUs (Refer to GROUP 54F, Explanation about the M.U.T.-III CAN Bus Diagnostics ).
    caution If the ignition switch is turned to the ON position without starting the engine, diagnosis code (past trouble) U1102 may be set on the combination meter after three minutes.

POSSIBLE CAUSES

  • Damaged harness wires and connectors
  • Malfunction of engine-A/T-ECU <A/T>
  • Malfunction of combination meter

DIAGNOSTIC PROCEDURE

Step 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result satisfactory?
Go to Step 2.
Repair the CAN bus lines. (Refer to GROUP 54F, Diagnosis - CAN Bus Diagnostics Table ). Repair the CAN bus line and go to Step 6.

Step 2. M.U.T.-III other system diagnosis code
Check whether the MPI system and the A/T system diagnosis codes are set or not.

Q. Is the diagnosis code set?
Diagnose MPI system or A/T system. (Refer to GROUP 13A, Troubleshooting or GROUP 13B, Troubleshooting or GROUP 23A, Troubleshooting )
Go to Step 3.

Step 3. M.U.T.-III other system diagnosis code
Check if a diagnosis code, which relates to CAN communication-linked systems below, is set.

    ETACS-ECU

    • Code No.U1101: engine-A/T-ECU <A/T> time-out (related to automatic transmission)
    A/C-ECU

    • Code No.U1101: engine-A/T-ECU <A/T> time-out (related to automatic transmission)

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

Step 4. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Turn the ignition switch to "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the check result satisfactory?
A poor connection, open circuit or other intermittent malfunction is present in the CAN bus lines between the engine-A/T-ECU <A/T> and the combination meter (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace engine-A/T-ECU <A/T> and then go to Step 6.

Step 5. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Turn the ignition switch to "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the check result satisfactory?
A poor connection, open circuit or other intermittent malfunction is present in the CAN bus lines between the engine-A/T-ECU <A/T> and the combination meter (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace combination meter and then go to Step 6.

Step 6. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Turn the ignition switch to "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the check result satisfactory?
The procedure is complete.
Go to Step 1.