Code No.U1120: Failure information of engine-ECU


DIAGNOSIS CODE SET CONDITIONS



PROBABLE CAUSES



  • Damaged wiring harness or connector
  • Malfunction of the engine-ECU
  • Malfunction of the A/T-ECU

DIAGNOSIS PROCEDURE

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

Q. Is the check result normal?
Go to Step 2.
Repair the CAN busline (Refer to GROUP54C, Diagnosis - Can Bus Diagnostic Chart ), and then go to Step 5.

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

Q. Is the diagnosis code set?
Diagnose the diesel fuel system (Refer to GROUP 13A, Troubleshooting ).
Go to Step 3.

STEP 3. M.U.T.-III diagnosis code
Reconfirm whether the diagnosis codes are output from A/T-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 engine-ECU. Then go to Step 4.
Intermittent malfunction in CAN busline between engine-ECU and A/T-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).

STEP 4. M.U.T.-III diagnosis code
Reconfirm whether the diagnosis codes are output from A/T-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 A/T-ECU. Then go to Step 5.
The procedure is complete.

STEP 5. M.U.T.-III diagnosis code
Reconfirm whether the diagnosis codes are output from A/T-ECU.

  • Erase the diagnosis codes being output.
  • Ignition switch: LOCK (OFF) to ON
  • Confirm whether the diagnosis codes are output.

Q. Is the diagnosis code output?
Go to Step 1.
The procedure is complete.