TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION
55A-29
YES :
Diagnose the ETACS-ECU. Refer to .
NO :
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.
• ETACS-ECU
U0141: ETACS-related time-out diagnosis code
Q: Is the diagnosis code set?
YES :
Go to Step 4
NO :
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?
YES :
Replace the ETACS-ECU, and then go to
Step 6.
NO :
A poor connection, open circuit or other
intermittent malfunction in the CAN bus line
between the ETACS-ECU and the 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?
YES :
Replace the A/C-ECU, and then go to Step
6.
NO :
A poor connection, open circuit or other
intermittent malfunction in the CAN bus line
between the ETACS-ECU and the A/C-ECU
(Refer to GROUP 00
− How to Cope with
Intermittent Malfunction ).
STEP 6. 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?
YES :
Return to Step 1.
NO :
The procedure is complete.
Code No. U0151: SRS CAN time-out
CAUTION
If diagnosis code No.U0151 is set in the 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 A/C-ECU receives air conditioner control-related
signals from the SRS-ECU via the CAN bus lines. If
the ECU cannot receive any of the air conditioner
control-related signals from the SRS-ECU, diagnosis
code U0151 will be stored.
COMMENTS ON TROUBLE SYMPTOM
Current trouble
• Connector(s) or wiring harness in the CAN bus
lines between the SRS-ECU and the A/C-ECU,
the power supply system to the SRS-ECU, the
SRS-ECU itself, or the A/C-ECU may be defec-
tive.
Past trouble
• Carry out diagnosis with particular emphasis on
connector(s) or wiring harness in the CAN bus
lines between the SRS-ECU and the A/C-ECU,
and the power supply system to the SRS-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 Mal-
function 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 Diagnos-
tic Flow ).