If diagnosis
code No. U0164 is set, be sure to diagnose the CAN bus line.
When replacing the ECU, always check that the communication circuit is normal.
DIAGNOSIS FUNCTION
If the signal from A/C-ECU cannot be received, the KOS-ECU sets diagnosis code
No. U0164.
PROBABLE CAUSES
Malfunction of CAN bus line
Malfunction of A/C-ECU
Malfunction of KOS-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use 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 ).
STEP 2. M.U.T.-III other system diagnosis code
Check if the A/C-ECU related diagnosis code is set.
Q.
Is the diagnosis code set?
Troubleshoot the A/C or heater (GROUP 55, Auto A/C Diagnosis ).
Go to Step 3.
STEP 3. M.U.T.-III other system diagnosis code
Check if diagnosis code No.U0164 is set to the combination meter.
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 to the KOS-ECU.
(1)Erase the diagnosis code.
(2)Turn the power supply mode of the engine switch from OFF to ON.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace the A/C-ECU.
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - 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)Turn the power supply mode of the engine switch from OFF to ON.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace KOS-ECU and register the ID codes (Refer to ).
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting 
).