Code No.U1120
Failures Information on Engine-ECU (Related to Engine)
caution
If diagnosis code U1120 is
set in the multi display station, always diagnose the CAN bus lines.
TROUBLE JUDGMENT
The multi display station receives the vehicle speed signal, average injected fuel amount
signal, vehicle speed pulse signal and atmospheric pressuure signal for the multi display station
from the engine-ECU via CAN bus lines. If failure information is sent to the vehicle speed signal,
average injected fuel amount signal, vehicle speed pulse signal and atmospheric pressuure signal
for the multi display station, diagnosis code U1120 will be set.
COMMENTS ON TROUBLE SYMPTOM
Current trouble
The engine-ECU or the multi display station may be defective.
Past trouble
Carry out diagnosis with particular emphasis on connector(s) or wiring harness between
the multi display station and the engine-ECU. For diagnosis procedures, refer to "How to treat
past trouble" (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points ).
POSSIBLE CAUSES
Damaged harness wires and connectors
Malfunction of engine-ECU
Malfunction of multi display station
DIAGNOSSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
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, Diagnosis -
Can Bus Diagnostics
Table ). Repair the CAN bus line and go to Step 6.
STEP 2. M.U.T.-III other system diagnosis code
Check whether the engine-ECU-related diagnosis code is set.
Q.
Is the diagnosis code set?
Diagnose the engine-ECU (Refer to GROUP 13A -
Troubleshooting ).
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 (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.
Replace the multi display station temporarily, and then check that the diagnosis code
is not reset.
(1)Replace the multi display station temporarily.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to "ON" position.
(4)Check if the diagnosis code is set.
Q.
Is the check result satisfactory?
Replace multi display station and then go to step 6.
Go to Step 5.
STEP 5. Check whether the diagnosis code is reset.
Replace the engine-ECU temporarily, and then check that the diagnosis code is not reset.
(1)Replace the engine-ECU temporarily.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to "ON" position.
(4)Check if the diagnosis code is set.
Q.
Is the check result satisfactory?
Replace engine-ECU and then go to step 6.
A poor connection, open circuit or other intermittent malfunction is present in
the lines between the centre display unit or multi display station 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.
).
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C, Diagnosis -
Can Bus Diagnostics
Table