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 or diesel fuel system diagnosis code is set.
Q.
Is the diagnosis code set?
Diagnose the MPI system or diesel fuel system. (Refer to GROUP 13A -Troubleshooting <1100>,
GROUP 13B -Troubleshooting <1300, 1500-MPI>,
GROUP 13C -Troubleshooting <1500-MPI-T/C>or
GROUP 13D -Troubleshooting <1500D>).
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. Multi centre display
Code No.U1120: Failure information on engine-ECU or engine-A-M/T-ECU (related
to engine)
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-M/T-ECU <Automated
manual transmission> 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 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.
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 6. Check whether the diagnosis code is reset.