P0A01-726

P310 HYBRID VEHICLE CONTROL: HYBRID CONTROL SYSTEM: P0A01-725: Motor Electronics Coolant Temperature Sensor Circuit Range / Performance

DTC P0A01-725 - Motor Electronics Coolant Temperature Sensor Circuit Range / Performance

DTC P0A01-726 - Motor Electronics Coolant Temperature Sensor Circuit Range / Performance

DESCRIPTION

The hybrid vehicle control ECU detects HV coolant temperature using the coolant temperature sensor built into the inverter. The inverter cooling system is the same as that for the MG2 and MG1, and operates independently of the engine cooling system. The hybrid vehicle control ECU controls the inverter cooling system to prevent overheating based on signals from the coolant temperature sensor. The ECU also monitors cooling system operation and detects malfunctions in the HV coolant temperature sensor and the circuit.

The inverter converts the high-voltage direct current of the HV battery into the alternating current for MG2, MG1, and MGR. The inverter generates heat during the conversion process, and this heat could damage the inverter if the cooling system is malfunctioning. Therefore, similar to MG2 and MG1, the inverter is cooled by a special cooling system consisting of an electric water pump, the cooling fan, and a radiator. This cooling system is independent of the engine cooling system. The hybrid vehicle control ECU monitors the electric water pump, cooling fan, and cooling system, and detects the following malfunctions.

INSPECTION PROCEDURE
CAUTION:
- Before inspecting the high-voltage system or disconnecting the low voltage connector of the inverter with converter assembly, take safety precautions such as wearing insulated gloves and removing the service plug grip to prevent electrical shocks. After removing the service plug grip, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.
- After disconnecting the service plug grip, wait for at least 5 minutes before touching any of the high-voltage connectors or terminals. After waiting for 5 minutes, check the voltage at the terminals in the inspection point in the inverter with converter assembly. The voltage should be 0 V before beginning work.
HINT: Waiting for at least 5 minutes is required to discharge the high-voltage capacitor inside the inverter with converter assembly.

PROCEDURE

1. CHECK DTC OUTPUT (HV)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (READY) and wait for 10 seconds or more.
(c) Select the following menu items: Powertrain / Hybrid Control / Trouble Codes.
(d) Check if DTCs are output.
Result:

B -- GO TO DTC CHART Diagnostic Trouble Code Descriptions
A -- Continue to next step.
2. CHECK QUANTITY OF HV COOLANT

(a) Check the coolant level in the inverter reserve tank.
(b) Check for coolant leaks.
Result:

HINT: After repairing the coolant leaks and adding coolant, perform the "Activate the Water Pump" active test (HV ECU active test item) and the "Control the Electric Cooling Fan" active test (ENHANCED OBDII active test item) and make sure that there are no malfunctions.

C -- CHECK FOR COOLANT LEAKS AND ADD COOLANT
B -- ADD HV COOLANT
A -- Continue to next step.
3. CHECK COOLANT HOSE

(a) Check if the hoses of the cooling system are kinked or clogged.
OK:
The hoses of the cooling system are not kinked or clogged.
NG -- CORRECT THE PROBLEM
OK -- Continue to next step.
4. CHECK CONNECTOR CONNECTION CONDITION (WATER PUMP WITH MOTOR AND BRACKET ASSEMBLY CONNECTOR)

(a) Check the connection of the water pump with motor and bracket assembly connector.
OK:
The connector is connected securely and there are no contact problems.
NG -- CONNECT SECURELY
OK -- Continue to next step.
5. PERFORM ACTIVE TEST USING TECHSTREAM (WATER PUMP)
(a) Turn the the power switch on (IG).
(b) Select the following menu items: Powertrain / Hybrid Control / Active Test / Activate the Water Pump.
(c) Perform the "Activate the Water Pump" active test for at least 1 minute.

(d) Check that there are ripples in the coolant in the inverter reserve tank.
OK:
There are ripples in the coolant in the inverter reserve tank as long as the active test is being performed.
NOTE: In addition to the active test, the water pump with motor and bracket assembly will also operate with the power switch on (READY). However, the water pump with motor and bracket assembly will not operate for 20 seconds after the power switch is turned on (READY).
HINT: The water pump with motor and bracket assembly will also operate in inspection mode.

NG -- CHECK FUSE (INV-W/P)
OK -- Continue to next step.
6. PERFORM ACTIVE TEST USING TECHSTREAM (COOLING FAN)
(a) Select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Electric Cooling Fan.
(b) Perform the "Control the Electric Cooling Fan" active test.
OK:
The cooling fan rotates.
NG -- CHECK COOLING FAN SYSTEM
OK -- Continue to next step.
7. CHECK CONNECTOR CONNECTION CONDITION (MG ECU CONNECTOR)
CAUTION: Be sure to wear insulated gloves.
(a) Turn the power switch off.
(b) Remove the service plug grip Removal.
NOTE: After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair manual because this may cause a malfunction.
(c) Remove the inverter cover Removal.
NOTICE:
- Wrap the round interlock terminal for the inverter cover with insulating tape to prevent it from shorting to ground.
- Be sure to prevent coolant in the inverter reserve tank from entering the inverter.
- Removing the inverter cover causes the MG ECU board to be exposed. Therefore, temporarily install the inverter cover for each area to be inspected.

(d) Check the connections of all MG ECU connectors.
OK:
The connectors are connected securely and there are no contact problems.
NG -- CONNECT SECURELY
OK -- REPLACE INVERTER WITH CONVERTER ASSEMBLY
8. CHECK FUSE (INV-W/P)

(a) Check if there is an open circuit in the fuse (INV-W/P) in the No. 2 engine room relay block.
OK:
There is no open circuit in the fuse (INV-W/P).
HINT: If the result is NG, replace the fuse (INV-W/P) with a new one.

NG -- REPLACE FUSE (INV-W/P)
OK -- Continue to next step.
9. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - WATER PUMP)

(a) Turn the power switch off.
(b) Disconnect the D35 connector from the hybrid vehicle control ECU.
(c) Disconnect the A52 water pump with motor and bracket assembly connector.
(d) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):

Standard resistance (Check for short):

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
10. CHECK HYBRID VEHICLE CONTROL ECU (IG)
(a) Connect the hybrid vehicle control ECU connector.
(b) Turn the power switch on (IG).

NG -- INSPECT WATER PUMP WITH MOTOR AND BRACKET ASSEMBLY
OK -- Continue to next step.
11. CHECK HYBRID VEHICLE CONTROL ECU (READY)
(a) Turn the power switch on (READY).

(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:

NG -- REPLACE HYBRID VEHICLE CONTROL ECU
OK -- REPLACE WATER PUMP WITH MOTOR AND BRACKET ASSEMBLY
12. INSPECT WATER PUMP WITH MOTOR AND BRACKET ASSEMBLY
(a) Turn the power switch off.

(b) Disconnect the D35 hybrid vehicle control ECU connector.
(c) Turn the power switch on (IG).
(d) Measure the voltage according to the value(s) in the table below.
Standard voltage:

NG -- REPLACE WATER PUMP WITH MOTOR AND BRACKET ASSEMBLY
OK -- REPLACE HYBRID VEHICLE CONTROL ECU