Code No.U1110: A/C-ECU timeout


caution
  • If diagnosis code No.U1110 is set in the ETACS-ECU, diagnose the CAN main bus line.
  • Whenever the ECU is replaced, ensure that the input and output signal circuits are normal.
  • For vehicles without automatic A/C, diagnosis code No. U1110 does not mean that there is a problem.
note When the diagnosis codes relating to the CAN communication error are set, make sure of the vehicle equipment. When the vehicle is not equipped with the system the ETACS-ECU communicates to, the diagnosis code is always output. This is not abnormal.

TROUBLE JUDGEMENT



COMMENT ON TROUBLE SYMPTOM


The M.U.T.-III shows a diagnosis code status as active.
  • Connector(s) or wiring harness in the CAN bus lines between the A/C-ECU and the ETACS-ECU, the power supply system to the A/C-ECU, the A/C-ECU itself, or the ETACS-ECU may be defective.
The M.U.T.-III shows a diagnosis code status as stored.
  • If diagnosis code No.U1110 is stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) in the CAN bus line between the A/C-ECU and the ETACS-ECU, and the power supply system to the A/C-ECU. For diagnosis procedures, refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Treat Past Trouble .
    note For a past trouble, you cannot 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 probable cause of the trouble by referring to the diagnosis code, which is set regarding the CAN communication-linked ECUs (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow ).

PROBABLE CAUSES



  • Malfunction of the A/C-ECU
  • Damaged harness wires and connectors

DIAGNOSIS PROCEDURE


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



Q. Is the check result normal?





STEP 2. Check the diagnosis code of the A/C.



Q. Is the diagnosis code set?





STEP 3. Check whether the diagnosis code is reset.



(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)On completion, check that the diagnosis code is reset.

Q. Is the diagnosis code set?





STEP 4. Check whether the diagnosis code is reset.



(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)On completion, check that the diagnosis code is reset.

Q. Is the diagnosis code set?





STEP 5. Check whether the diagnosis code is reset.



(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)On completion, check that the diagnosis code is reset.

Q. Is the diagnosis code set?