HYBRID / BATTERY CONTROL: BATTERY ECU (for LITHIUM-ION BATTERY): REMOVAL; 2021 MY Avalon HV [08/2020

Last Modified: 08-21-2023	6.11:8.1.0	Doc ID: RM100000001PZ6L
Model Year Start: 2021	Model: Avalon HV	Prod Date Range: [08/2020 - 08/2021]
Title: HYBRID / BATTERY CONTROL: BATTERY ECU (for LITHIUM-ION BATTERY): REMOVAL; 2021 MY Avalon HV [08/2020 - 08/2021]

REMOVAL

CAUTION / NOTICE / HINT

The necessary procedures (adjustment, calibration, initialization or registration) that must be performed after parts are removed and installed, or replaced during battery ECU assembly removal/installation are shown below.

Necessary Procedures After Parts Removed/Installed/Replaced

Replaced Part or Performed Procedure	Necessary Procedure	Effect/Inoperative Function when Necessary Procedure not Performed
*: When performing learning using the Techstream. Click here
Auxiliary battery terminal is disconnected/reconnected	Perform steering sensor zero point calibration	Lane departure alert system (w/ Steering Control)
		Pre-collision system
		Intelligent clearance sonar system*
		Lighting System (for HV Model with Cornering Light)
	Memorize steering angle neutral point	Parking assist monitor system
	Memorize steering angle neutral point	Panoramic view monitor system
Replacement of battery ECU assembly	Current sensor offset learning	DTCs are stored

CAUTION:

Orange wire harnesses and connectors indicate high-voltage circuits. To prevent electric shock, always follow the procedure described in the repair manual.
Click here
To prevent electric shock, wear insulated gloves when working on wire harnesses and components of the high voltage system.

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
The type of battery ECU assembly to be used varies depending on the vehicle model.

The type of battery ECU assembly can be confirmed by the color of the label.

*a	Black Label

If the wrong type of battery ECU assembly is installed, the power switch cannot be turned on (READY).
After installing the battery ECU assembly, perform the following to check that the power switch can be turned on (READY).
- Turn the power switch on (READY).
- Turn the power switch off and wait for 30 seconds or more.
- Turn the power switch on (READY) again.

PROCEDURE

1. WHEN REPLACING BATTERY ECU ASSEMBLY

HV battery learning values are stored in the battery ECU assembly and ECM and are used to detect malfunctions and illuminate the hybrid battery indicator light in the combination meter assembly. When either of these ECUs is replaced, the new ECU receives the HV battery learning values from the other ECU and stores them.

NOTICE:

Do not replace the battery ECU assembly and ECM at the same time as the HV battery learning values will be lost. However, if it is necessary to replace both ECUs at the same time, replace them by following the procedure below.
Do not replace the battery ECU assembly or ECM with a used one from another vehicle.

(a) Procedure when replacing both battery ECU assembly and ECM:

(1) Disconnect the cable from the negative (-) auxiliary battery terminal.

(2) Replace either ECU.

(3) Connect the cable to the negative (-) auxiliary battery terminal.

(4) Turn the power switch on (READY) and wait for 5 minutes or more.

(5) Turn the power switch off and disconnect the cable from the negative (-) auxiliary battery terminal.

(6) Replace the other ECU.

(7) Connect the cable to the negative (-) auxiliary battery terminal.

(8) Check that the power switch can be turned on (READY).

HINT:

If the battery ECU assembly and ECM are replaced at the same time without following the above procedure, replace either of the ECUs with its original one and then replace it again by following the above procedure. If the correct procedure is not followed, perform the procedure again from the beginning.

2. REMOVE SERVICE PLUG GRIP

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3. DISCONNECT ENGINE ROOM MAIN WIRE

Click here

4. REMOVE CONNECTOR COVER ASSEMBLY

Click here

5. CHECK TERMINAL VOLTAGE

Click here

6. INSTALL CONNECTOR COVER ASSEMBLY

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7. CONNECT ENGINE ROOM MAIN WIRE

Click here

8. REMOVE NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY

Click here

9. REMOVE REAR DOOR SCUFF PLATE LH

Click here

10. REMOVE REAR UNDER SIDE COVER LH

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11. REMOVE REAR DOOR SCUFF PLATE RH

HINT:

Use the same procedure as for the LH side.

12. REMOVE REAR UNDER SIDE COVER RH

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13. REMOVE REAR UNDER COVER

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14. REMOVE REAR SEAT CUSHION LEG SUB-ASSEMBLY

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15. REMOVE NO. 1 HV BATTERY COVER PANEL RH

Click here

16. REMOVE HYBRID BATTERY HOSE ASSEMBLY

Click here

17. DISCONNECT FLOOR WIRE

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18. REMOVE NO. 4 HV BATTERY PROTECTOR

Click here

19. DISCONNECT FLOOR WIRE

Click here

20. REMOVE UPPER HV BATTERY COVER SUB-ASSEMBLY

CAUTION:

Be sure to wear insulated gloves and protective goggles.

(a) Remove the 5 bolts, 7 nuts and upper HV battery cover sub-assembly from the HV battery.

*a	Bolt
*b	Nut

21. REMOVE NO. 1 HV BATTERY HOSE

CAUTION:

Be sure to wear insulated gloves and protective goggles.

(a) Remove the 2 clips.

(b) Disengage the 2 claws to remove the No. 1 HV battery hose from the HV battery.

22. REMOVE BATTERY ECU ASSEMBLY

CAUTION:

Be sure to wear insulated gloves and protective goggles.

(a) Disengage the clamp.

(b) Move the lock lever while pushing the lock, and disconnect the 3 battery ECU assembly connectors.

NOTICE:

Make sure to release the lock of the lock lever before moving it.

*a	Lever Lock

If the connector cannot be disconnected, check if the lock lever is completely unlocked.
Insulate each disconnected high-voltage connector with insulating tape. Wrap the connector from the wire harness side to the end of the connector.

NOTICE:

If the battery ECU assembly has been struck or dropped, replace it.