Code No.U1120: Engine Data Error


caution
  • If diagnosis code U1120 is set in the transfer-ECU, always diagnose the CAN main bus line.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.

DIAGNOSIS CODE SET CONDITIONS


Current trouble
  • The engine-ECU <4M4> or engine-A/T-ECU <6G7>, or the transfer-ECU 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-ECU <4M4> or engine-A/T-ECU <6G7> and the transfer-ECU, and the power supply system to the engine-ECU <4M4> or engine-A/T-ECU <6G7>. 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 . 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 54D - CAN Bus Line Diagnostic Flow ).

PROBABLE CAUSES



  • Damaged wiring harness or connector
  • Malfunction of the transfer-ECU
  • Malfunction of the engine-ECU <4M4>
  • Malfunction of the engine-A/T-ECU <6G7>

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Using M.U.T.-III, perform CAN bus line diagnosis.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54D - Troubleshooting ). and then go to Step 4.

STEP 2. M.U.T.-III other system diagnosis codes
Check whether the fuel system diagnosis codes are set or not.

Q. Is the diagnosis code set?
YES : Diagnose the fuel system (Refer to GROUP 13D - Troubleshooting <6G7>, or GROUP 13B - Troubleshooting <4M4>).
Go to Step 3.

STEP 3. M.U.T.-III diagnosis code
Reconfirm whether the diagnosis codes are set from transfer-ECU.
(1)Erase the diagnosis code.
(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Go to Step 4.
Intermittent malfunction in CAN bus line between engine-ECU <4M4> or engine-A/T-ECU <6G7> and transfer-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

STEP 4. Replace the engine-ECU <4M4> or engine-A/T-ECU <6G7>
After replacing the engine-ECU <4M4> or engine-A/T-ECU <6G7>, re-check the transfer diagnosis code output.

Q. Is the diagnosis code set?
Replace the transfer-ECU.
The check is end.