Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Cooling System

DESCRIPTION

The cause of the malfunction may be the cooling system.

Check whether the grille is blocked, whether coolant is leaking, the radiator fan operating condition and whether coolant has frozen.

SYSTEM DESCRIPTION

The inverter converts the high-voltage direct current of the HV battery into alternating current for the generator (MG1) and motor (MG2). The inverter generates heat during the conversion process. Therefore, the inverter is cooled by a special cooling system consisting of the inverter water pump assembly, the cooling fan, and a radiator. This cooling system is independent of the engine cooling system. The hybrid vehicle control ECU monitors the inverter water pump assembly, cooling fan and cooling system, and detects malfunctions.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

This diagnostic procedure is referenced to in the diagnostic procedure of several DTCs.

If the result of this diagnostic procedure is normal, proceed as directed in the procedure for the DTC.

CAUTION:

• Before the following operations are conducted, take precautions to prevent electric shock by turning the power switch off, wearing insulated gloves, and removing the service plug grip from HV battery.
  • Inspecting the high-voltage system
  • Disconnecting the low voltage connector of the inverter with converter assembly
  • Disconnecting the low voltage connector of the HV battery
• To prevent electric shock, make sure to remove the service plug grip to cut off the high voltage circuit before servicing the vehicle.
• After removing the service plug grip from the HV battery, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.
• After removing the service plug grip, wait for at least 10 minutes before touching any of the high-voltage connectors or terminals. After waiting for 10 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.

  *a	Without waiting for 10 minutes

  Click here

  HINT:

  Waiting for at least 10 minutes is required to discharge the high-voltage capacitor inside the inverter with converter assembly.

NOTICE:

After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

Click here

PROCEDURE

(a) Make sure that the front side of the radiator grille is not blocked with anything.

(b) Ask the customer if the front side of the radiator grille was blocked with anything.

HINT:

If the radiator grille is blocked, the inverter coolant temperature will increase and this DTC may be stored.

B

IF EQUIPPED, EXPLAIN TO CUSTOMER THAT OPTIONAL COMPONENTS WILL BE REMOVED

A

(a) Check the HV coolant level in the inverter reserve tank.

(b) Check for HV coolant leaks.

HINT:

• After repairing the HV coolant leaks and adding coolant, perform the Active Tests "Activate the Inverter Water Pump" (Hybrid Control System) and "Control the Cooling Fan Duty Ratio" (Engine Control System) and make sure that there are no malfunctions.
• If there are signs of coolant leakage around the connecting parts of a hose and the inverter with converter assembly, replace the hose with a new one.

B

ADD HV COOLANT

C

INSPECT FOR COOLANT LEAK AND ADD COOLANT

A

(a) Check that the cooling system hoses are not kinked or clogged.

OK:

The cooling system hoses are not kinked or clogged.

NG

REPAIR OR REPLACE COOLANT HOSE

OK

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Enter the following menus: Powertrain / Engine / Active Test / Control the Engine Cooling Fan Duty Ratio.

(d) Perform the "Control the Engine Cooling Fan Duty Ratio" Active Test.

OK:

(e) Turn the power switch off.

B

CHECK COOLING FAN SYSTEM

A

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Enter the following menus: Body Electrical / Grill Shutter / Utility / Grill Shutter Control Mode Switching.

(d) According to the display on the Techstream, change the grille shutter control mode from normal mode to maintenance mode.

(e) Enter the following menus: Body Electrical / Grill Shutter / Active Test / Shutter Closing Operation Lock Detection / Data List / Shutter Operation Lock Detection Result for Active Test.

(f) According to the display on the Techstream, perform the Active Test and read the value of Data List item Shutter Operation Lock Detection Result for Active Test.

OK:

"Normal" is displayed.

(g) Enter the following menus: Body Electrical / Grill Shutter / Active Test / Shutter Opening Operation Lock Detection / Data List / Shutter Operation Lock Detection Result for Active Test.

(h) According to the display on the Techstream, perform the Active Test and read the value of Data List item Shutter Operation Lock Detection Result for Active Test.

OK:

"Normal" is displayed.

HINT:

When the value of Data List item Shutter Operation Lock Detection Result for Active Test is "Normal", it can be determined that the grille shutter system is normal.

(i) Enter the following menus: Body Electrical / Grill Shutter / Utility / Grill Shutter Control Mode Switching.

(j) According to the display on the Techstream, change the grille shutter control mode from maintenance mode to normal mode.

(k) Turn the power switch off.

NG

CHECK GRILLE SHUTTER SYSTEM

OK

NOTICE:

• Make sure that the HV coolant level is above the low line of the inverter reserve tank.
• Be sure to perform the inspection with the auxiliary battery voltage at 11 V or more.

HINT:

When the auxiliary battery voltage is low, the inverter water pump assembly may not operate.

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Enter the following menus: Powertrain / Hybrid Control / Active Test / Activate the Inverter Water Pump.

(d) Select the Data List item "Inverter Water Pump Revolution".

(e) According to the display on the Techstream, perform the Active Test "Activate the Inverter Water Pump" and check the value of the Data List item "Inverter Water Pump Revolution".

OK:

HINT:

• Perform the Active Test with the inverter coolant temperature between -15 and 65°C (5 to 149°F).
• When the inverter water pump assembly is not operating, the Data List item "Inverter Water Pump Revolution" displays a value 200 rpm or less.

(f) Turn the power switch off.

NG

GO TO STEP 9

OK

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (READY) and wait for 1 minute with the engine stopped.

(c) Enter the following menus: Powertrain / Hybrid Control / Data List / Generator Inverter Calculated Temperature, Motor Inverter Temperature, Boosting Converter Temperature (Upper), Boosting Converter Temperature (Lower) and Inverter Coolant Water Temperature.

(d) Read the Data List with the engine stopped.

HINT:

The lower limit temperature that can be displayed for "Generator Inverter Calculated Temperature", "Motor Inverter Temperature", "Boosting Converter Temperature (Upper)" and "Boosting Converter Temperature (Lower)" is 15°C (59°F). The lower limit temperature for "Inverter Coolant Water Temperature" is -40°C (-40°F). The "Inverter Coolant Water Temperature" value displayed on the Techstream may be lower than the others, but this is not a malfunction.

(e) Turn the power switch off.

B

REPLACE INVERTER WITH CONVERTER ASSEMBLY

A

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

(d) Read the freeze frame data item "Ambient Temperature" using the Techstream.

(e) Check if the freeze frame data item "Ambient Temperature" is below the freezing temperature of the HV coolant.

HINT:

• HV coolant (SLLC) with a 30% concentration freezes at -15°C (5°F) and HV coolant (SLLC) with a 50% concentration freezes at -35°C (-31°F).
• If the HV coolant freezes in the HV radiator or inverter water pump, the coolant temperature in the inverter with converter assembly rises because the HV coolant cannot circulate. As a result, a DTC may be stored.
• A DTC is stored when the inverter water pump impeller cannot rotate due to freezing of the HV coolant.
• If DTCs are output due to freezing of the LLC, the problem symptom cannot be reproduced. Check the LLC replacement history and whether the LLC was frozen based on the ambient temperature when the DTCs were stored.

(f) Turn the power switch off.

A

COOLING SYSTEM NORMAL (PERFORM NEXT STEP FOR REFERENCED DTC)

B

REPLACE HV COOLANT

Click here

NG

CONNECT SECURELY

OK

(a) Check the connector connections and contact pressure of the relevant terminals for the inverter water pump assembly connector. Click here OK: The connector is connected securely, the terminals are not deformed or corroded and there are no contact problems.

NG

CONNECT SECURELY

OK

(a) Disconnect the A23 hybrid vehicle control ECU connector.

(b) Disconnect the X1 inverter water pump assembly connector.

(c) Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open): Tester Connection Condition Specified Condition A23-13 (IWP) - X1-3 (SWP) Power switch off Below 1 Ω Standard Resistance (Check for Short): Tester Connection Condition Specified Condition A23-13 (IWP) or X1-3 (SWP) - Body ground and other terminals Power switch off 10 kΩ or higher

*a Rear view of wire harness connector (to Hybrid Vehicle Control ECU) *b Front view of wire harness connector (to Inverter Water Pump Assembly)

(d) Reconnect the X1 inverter water pump assembly connector.

(e) Reconnect the A23 hybrid vehicle control ECU connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

NOTICE:

Be sure to perform the inspection with the auxiliary battery voltage at 11 V or more.

HINT:

When the auxiliary battery voltage is low, the inverter water pump assembly may not operate.

(a) Connect the Techstream to the DLC3.

(b) Remove the INV W/PMP fuse from the No. 4 relay block.

*1 No. 4 Relay Block *2 INV W/PMP Fuse

(c) Turn the power switch on (IG).

(d) Enter the following menus: Powertrain / Hybrid Control / Data List / Inverter Water Pump Revolution.

(e) According to the display on the Techstream, read the Data List.

Standard:

(f) Turn the power switch off.

(g) Install the INV W/PMP fuse.

NG

REPLACE HYBRID VEHICLE CONTROL ECU

OK

(a) Disconnect the A23 hybrid vehicle control ECU connector.

(b) Turn the power switch on (IG).

(c) Measure the voltage according to the value(s) in the table below. Standard Voltage: Tester Connection Condition Specified Condition A23-13 (IWP) - G46-6 (E1) Power switch on (IG) 11 to 14 V NOTICE: Turning the power switch on (IG) with the hybrid vehicle control ECU connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

*a Component with harness connected (Hybrid Vehicle Control ECU) *b Rear view of wire harness connector (to Hybrid Vehicle Control ECU)

(d) Turn the power switch off.

(e) Reconnect the A23 hybrid vehicle control ECU connector.

NG

GO TO STEP 15

OK

(a) Connect an oscilloscope between the hybrid vehicle control ECU terminals specified in the table below.

(b) Turn the power switch on (IG).

(c) While turning the power switch on (IG), check the waveform between the hybrid vehicle control ECU terminals. Item Content Terminal A23-13 (IWP) - G46-6 (E1) Equipment Setting 5 V/DIV., 50 ms./DIV. Condition Power switch on (IG) OK: Waveform duty ratio is between 3% and 9%.

*a Component with harness connected (Hybrid Vehicle Control ECU)

(d) Turn the power switch off.

NG

REPLACE HYBRID VEHICLE CONTROL ECU

OK

Click here

NEXT

(a) After replacing the inverter water pump assembly, add HV coolant and perform air bleeding.

Click here

NEXT

END