A25A-FXS (ENGINE CONTROL): ECM: REMOVAL; 2021 MY Avalon HV [08/2020

Last Modified: 08-21-2023	6.11:8.1.0	Doc ID: RM100000001PX5C
Model Year Start: 2021	Model: Avalon HV	Prod Date Range: [08/2020 - 08/2021]
Title: A25A-FXS (ENGINE CONTROL): ECM: 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 ECM 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 ECM	Perform Vehicle Identification Number (VIN) registration	MIL illuminates

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
If the ECM has been struck or dropped, replace it.
Perform Vehicle Identification Number (VIN) registration when replacing the ECM.
Click here

PROCEDURE

1. PRECAUTION

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 the battery ECU assembly and ECM 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 LUGGAGE TRIM SERVICE HOLE COVER

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3. DISCONNECT CABLE FROM NEGATIVE AUXILIARY BATTERY TERMINAL

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4. REMOVE ECM

(a) Rotate the 2 levers while pushing the locks, and disconnect the 2 ECM connectors.

NOTICE:

After disconnecting the ECM connectors, make sure that dirt, water and other foreign matter does not contact the connecting parts of the ECM connectors.

(b) Remove the bolt and separate the engine wire from the No. 2 ECM bracket.

(d) Remove the 2 nuts and ECM.

NOTICE:

If the ECM has been struck or dropped, replace it.

5. REMOVE NO. 1 ECM BRACKET

(a) Remove the 2 screws and No. 1 ECM bracket from the ECM.

6. REMOVE NO. 2 ECM BRACKET

(a) Remove the 2 screws and No. 2 ECM bracket from the ECM.