Code No. U1120: Failure information on engine-ECU or engine-A-M/T-ECU (Related to Engine)

caution

If diagnosis code No. U1120 is set in the combination meter, diagnose the CAN main bus line.

TROUBLE JUDGMENT

The combination meter communicates with the engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> via CAN bus line. If failure information is sent from the engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission>, diagnosis code No. U1120 will be set.

COMMENTS ON TROUBLE SYMPTOM

The M.U.T.-III shows a diagnosis code status as active.

The engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> or the combination meter may be defective.

The M.U.T.-III shows a diagnosis code status as stored.

Carry out diagnosis with particular emphasis on connector(s) or wiring harness between the engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> and the combination meter. For diagnosis procedures, refer to "How to cope with past trouble" (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points ).

PROBABLE CAUSES

Damaged harness wires and connectors
Malfunction of engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission>
Malfunction of combination meter

DIAGNOSIS PROCEDURE

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

warning

Since the radiator fan rotates during CAN bus line diagnostics, make sure that no one is servicing the engine compartment before diagnosing the CAN bus line. Since the CAN communication stops when diagnosing the CAN bus line, the ETACS-ECU detects the time-out of the engine-ECU, and activates the radiator fan to prevent overheating as fail-safe.

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 54C, Troubleshooting

). Repair the CAN bus line and go to Step 6.

STEP 2. M.U.T.-III other system diagnosis code

Check if an MPI system diagnosis code is set.

Q. Is the diagnosis code set?

Diagnose the MPI system. Refer to GROUP 13A, Troubleshooting

<1100>, GROUP 13B, Troubleshooting

<1300, except 1500-T/C> or GROUP 13C, Troubleshooting

<1500-T/C>. And then go to Step 3.

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.
A/C-ECU

Code No. U1120: Failure information on engine-ECU or engine-A-M/T-ECU (related to engine)

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 diagnosis code set?

Replace engine-ECU <M/T> or engine-A/T-ECU Then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding

). Perform the variant coding, and then go to Step 6.

A poor connection, open circuit or other intermittent malfunction is present in the lines between the engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> and the combination meter (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

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 diagnosis code set?

Replace the combination meter. Then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding

). Perform the variant coding, 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?

Go to Step 1.

The procedure is complete.