The 5-V power is supplied from EV-ECU to the coolant temperature sensor, then the MCU coolant temperature is converted to the voltage and output to the EV-ECU.
DIAGNOSIS CODE SET CONDITIONS
When the coolant temperature 70°C or more continues for 5 seconds or longer, the diagnosis code No. P0A01 will be set.
note
The diagnosis code may be set by some driving operations such as high load, low-speed driving, or overuse of cooling.
PROBABLE CAUSES
Malfunction of the system cooling such as radiator, water pump, coolant
Malfunction of the coolant temperature sensor
Malfunction of the EV-ECU
DIAGNOSIS PROCEDURE
STEP 1. Coolant check
Refer to GROUP 14 - On-vehicle Service - Coolant Level Check .
Q.
Is the check result normal?
Go to Step 2.
Add or replace the coolant. Refer to GROUP 14 - On-vehicle Service - Coolant Replacement .)
STEP 2. M.U.T.-III actuator test
Conduct the actuator test, and check the water pump, cooling fan relay (LO), cooling fan relay (HI), and cooling fan.(Refer to .)
Actuator test
Item No. 3 : Water pump drive
Item No. 4 : Radiator fan 1 drive
Item No. 5 : Radiator fan 2 drive
OK: The water pump, cooling fan relay (LO), cooling fan relay (HI), and cooling fan operate normally.
Q.
Is the check result normal?
Go to Step 3.
Carry out troubleshooting for the EV-ECU diagnosis code No. P0A05 (refer to ), P0691, P0692 (refer to ), P0693, or P0694 (refer to ).
STEP 3. M.U.T.-III data list
Check the service data of the coolant temperature sensor.(Refer to .)
Item No. 82 : Coolant temperature sensor voltage
Q.
Is the check result normal?
Go to Step 4.
Replace the coolant temperature sensor. (Refer to GROUP 14 - On-vehicle Service - Coolant Temperature Sensor Check and Replace .) Then go to Step 5.
STEP 4. Diagnosis code recheck
Check again if the diagnosis code is set to the EV-ECU.
(1)Erase the stored diagnosis code.
(2)Set the electric motor switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace the EV-ECU. (Refer to .) Then go to Step 5.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .)
STEP 5. Diagnosis code recheck
Check again if the diagnosis code is set to the EV-ECU.
(1)Erase the stored diagnosis code.
(2)Set the electric motor switch from the LOCK (OFF) position to the ON position.
.
Go to Step 2.
Add or replace the coolant. Refer to GROUP 14 - On-vehicle Service - Coolant Replacement 