If diagnosis code No.U0141 is set in the heater controller
assembly (A/C-ECU), diagnose the CAN main bus line.
caution
Whenever the ECU is replaced, ensure that the communication
circuit is normal.
TROUBLE JUDGMENT
The heater controller assembly (A/C-ECU) receives air conditioner operation-related signal
from the ETACS-ECU via the CAN bus lines. If the heater controller assembly (A/C-ECU) can not
receive the air conditioner operation-related signal at all on the ETACS-ECU, diagnosis code
No.U0141 will be set.
COMMENTS ON TROUBLE SYMPTOM
Current trouble
Connector(s) or wiring harness in the CAN bus lines between the ETACS-ECU and the
heater controller assembly (A/C-ECU), the power supply system to the ETACS-ECU, the ETACS-ECU
itself, or the A/C-ECU may be faulty.
Past trouble
Carry out diagnosis with particular emphasis on connector(s) or wiring harness in
the CAN bus lines between the ETACS-ECU and the heater controller assembly (A/C-ECU), and the
power supply system to the ETACS-ECU. For diagnosis procedures, refer to "How to treat past
trouble" (Refer to GROUP 00 -
How to Treat Past Trouble ).
note
For a past trouble, you can not 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 Cope with Intermittent
Malfunction and check the CAN bus lines. You can narrow down
the possible 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 ).
caution
If the ignition switch is turned on without starting the engine
and then three minutes pass, the heater controller assembly (A/C-ECU) may store U0141 as past
trouble.
PROBABLE CAUSES
Damaged wiring harness or connectors
Malfunction of the ETACS-ECU
Malfunction of the heater controller assembly (A/C-ECU)
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 lines (Refer to GROUP 54C, Troubleshooting ).
On completion, go to Step 6.
STEP 2. M.U.T.-III other system diagnosis code
Check whether the ETACS-related diagnosis code is set.
Q.
Is the diagnosis code set?
Diagnose the ETACS-ECU. Refer to .
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.
Combination meter U0141: ETACS-ECU timeout
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)Ignition switch: LOCK (OFF) to ON
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace the ETACS-ECU, and then go to Step 6.
A poor connection, open circuit or other intermittent malfunction in the CAN bus
line between the ETACS-ECU and the heater controller assembly (A/C-ECU) (Refer to GROUP 00 -
How
to Cope with Intermittent Malfunction ).
STEP 5. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Ignition switch: LOCK (OFF) to ON
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace the heater controller assembly (A/C-ECU), and then go to Step 6.
A poor connection, open circuit or other intermittent malfunction in the CAN bus
line between the ETACS-ECU and the heater controller assembly (A/C-ECU) (Refer to GROUP 00 -
How
to Cope with Intermittent Malfunction ).
STEP 6. Check whether the diagnosis code is reset.
).
