Code No.U1100:
Engine-ECU Time-out (Related to Engine) Code No.U1101: A/T-ECU Time-out (Related
to A/T)
caution
If diagnosis
code No.U1100 or U1101 is set in the ETACS, diagnose the CAN main bus line.
Whenever the ECU is replaced, ensure that the communication circuit is normal.
For M/T-vehicles, diagnosis code No. U1101 does not mean that there is
a problem..
TROUBLE JUDGMENT
Diagnosis code No.U1100
The ETACS-ECU receives engine control system-related signals from the engine-ECU through
the CAN bus lines. If the ECU cannot receive the engine control system-related signal at all,
diagnosis code No.U1100 will be set.
Diagnosis code No.U1101
The ETACS-ECU receives the transmission control signals from the A/T-ECU <A/T>
via
CAN bus lines. If the ECU cannot receive the transmission control signal at all, diagnosis code
No.U1101 will be set.
COMMENT ON TROUBLE SYMPTOM
The M.U.T.-III shows a diagnosis code status as active.
Connector(s) or wiring harness in the CAN bus lines between the ETACS-ECU and the
engine-ECU or the A/T-ECU <A/T>, the power supply circuits
to the engine-ECU or the A/T-ECU <A/T>
itself may be defective.
The M.U.T.-III shows a diagnosis code status as stored.
If diagnosis code No.U1100 or U1101 is set as past trouble, carry out diagnosis
with particular emphasis on wiring and connector(s) in the CAN bus lines between the ETACS-ECU
and the engine-ECU or the A/T-ECU <A/T>, or power supply
to the engine-ECU or the A/T-ECU <A/T>. For diagnosis procedures,
refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points -
How
to Treat Past Trouble .
note
For a past trouble, you cannot 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 -
How to Cope with Intermittent Malfunctions and
check the CAN bus lines. You can narrow down the probable cause of the trouble by referring
to the diagnosis code, which is set regarding the CAN communication-linked ECUs (Refer to GROUP 54C -
CAN
Bus Line Diagnostic Flow ).
PROBABLE CAUSES
Malfunction of the engine-ECU or the A/T-ECU <A/T>
Malfunction of the CAN bus
DIAGNOSIS 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 normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C -
Troubleshooting ).
On completion, go to Step 6.
STEP 2. Check the diagnosis code of the engine-ECU or the A/T-ECU <A/T>.
Check if the diagnosis code is set in either of the engine-ECU or the A/T-ECU <A/T>.
Q.
Is the diagnosis code set?
Diagnose the engine-ECU or the A/T-ECU (Refer to GROUP 13A -
Troubleshooting <engine-ECU>
or GROUP 23A Troubleshooting <A/T-ECU>). On completion,
go to Step 6.
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.
ABS-ECU U1100: Engine-ECU time-out or U1101: A/T-ECU time-out <A/T>
Q.
Is the diagnosis code set?
Go to Step 5.
Go to Step 4.
STEP 4. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the ETACS-ECU.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)On completion, check that the diagnosis code is reset.
Q.
Is the check result normal?
A poor connection, open circuit or other intermittent malfunction is present in
the CAN bus lines between the engine-ECU or the A/T-ECU <A/T>
and the
ETACS-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points -
How
to Cope with Intermittent Malfunctions ).
Replace the engine-ECU or the A/T-ECU <A/T>.
Then, carry out the CAN bus diagnostics.Then go to Step 6.
STEP 5. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the ETACS-ECU.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)On completion, check that the diagnosis code is reset.
Q.
Is the check result normal?
A poor connection, open circuit or other intermittent malfunction is present in
the CAN bus lines between the engine-ECU or the A/T-ECU <A/T>
and the
ETACS-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points -
How
to Cope with Intermittent Malfunctions ).
Replace the ETACS-ECU. Then, carry out the CAN bus diagnostics. Then go to Step 6
.
STEP 6. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set to the ETACS-ECU.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)On completion, check that the diagnosis code is reset.
.
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C -
Troubleshooting