Last Modified: 08-21-2023 6.11:8.1.0 Doc ID: RM100000001R1J0
Model Year Start: 2021 Model: Avalon Prod Date Range: [08/2020 -           ]
Title: SEAT: FRONT POWER SEAT CONTROL SYSTEM (for Gasoline Model with Memory): Power Seat does not Return to Memorized Position; 2021 - 2022 MY Avalon [08/2020 -        ]

Power Seat does not Return to Memorized Position

DESCRIPTION

When the M1 or M2 switch of the seat memory switch is pressed, the outer mirror control ECU assembly sends a switch signal to the main body ECU (multiplex network body ECU) via CAN communication. Then, the main body ECU (multiplex network body ECU) sends a recall request signal to the position control ECU assembly. The position control ECU assembly operates each motor to move the seat to the memorized position.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • The seat position will not be stored if the SET switch and 2 or more of the seat memory switches (for example, M1 switch and M2 switch) are pressed simultaneously.

    If a memorizing operation has failed, release all of the switches. The seat memory function will not operate unless the switches are released.

  • The seat will not return to the memorized position if 2 or more of the seat memory switches (for example, M1 switch and M2 switch) are pressed simultaneously.

    If a restoring operation has failed, release all of the switches. The seat memory restoring function will not operate unless the switches are released.

  • The front power seat control system (w/ Memory) uses the CAN communication system. First, confirm that there are no malfunctions in the CAN communication system. Refer to How to Proceed with Troubleshooting.

    Click here 2019 - 2022 MY Avalon [04/2018 -        ]; SEAT: FRONT POWER SEAT CONTROL SYSTEM (for Gasoline Model with Memory): HOW TO PROCEED WITH TROUBLESHOOTING

  • Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

    Click here 2021 - 2022 MY Avalon [08/2020 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION

PROCEDURE

1.

CHECK FRONT POWER SEAT CONTROL OPERATION

(a) Check that each function of the power seat operates normally by using the front power seat switch LH.

Click here 2019 - 2022 MY Avalon [04/2018 -        ]; SEAT: FRONT POWER SEAT CONTROL SYSTEM (for Gasoline Model with Memory): OPERATION CHECK

OK:

Each function of the power seat operates normally using the front power seat switch LH.

NG

GO TO PROBLEM SYMPTOMS TABLE

OK

2.

CHECK SEAT POSITION MEMORY FUNCTION

(a) Check the seat position memory function.

Click here 2019 - 2022 MY Avalon [04/2018 -        ]; SEAT: FRONT POWER SEAT CONTROL SYSTEM (for Gasoline Model with Memory): OPERATION CHECK

OK:

Seat position memory function is normal.

NG

GO TO OTHER DIAGNOSIS PROCEDURE (Power Seat Position is not Memorized)

OK

3.

CHECK SEAT POSITION RESTORING FUNCTION

(a) Under each of the following conditions, check that the seat position restoring function operates by pressing the M1 or M2 switch.

Click here 2019 - 2022 MY Avalon [04/2018 -        ]; SEAT: FRONT POWER SEAT CONTROL SYSTEM (for Gasoline Model with Memory): OPERATION CHECK

  • The engine switch is on (IG), and the shift lever is in P.*1
  • Within 180 seconds after the driver door is opened with the engine switch off.*2
  • Within 60 seconds after the driver door is opened and then closed with the engine switch off.*3

Result

Proceed to

Seat position restoring function does not operate at all.

A

Seat position restoring function does not operate when the condition is *1.

B
  • Seat position restoring function does not operate when the condition is *2.
  • Seat position restoring function does not operate when the condition is *3.

C
B

GO TO STEP 7

C

GO TO STEP 10

A

4.

READ VALUE USING TECHSTREAM (SEAT POSITION MEMORY)

(a) Store a seat position in memory for the M1 and M2 switches.

Click here 2019 - 2022 MY Avalon [04/2018 -        ]; SEAT: FRONT POWER SEAT CONTROL SYSTEM (for Gasoline Model with Memory): OPERATION CHECK

(b) Connect the Techstream to the DLC3.

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

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Driver Seat / Data List.

(f) Read the Data List according to the display on the Techstream.

Body Electrical > Driver Seat > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Seat Memory No1

Seat position memorized with M1 switch

Mem or Not Mem

Mem: Memorized

Not Mem: Not memorized

-

Seat Memory No2

Seat position memorized with M2 switch

Mem or Not Mem

Mem: Memorized

Not Mem: Not memorized

-

Body Electrical > Driver Seat > Data List

Tester Display

Seat Memory No1

Seat Memory No2

OK:

Mem is displayed on the Techstream screen.

NG

GO TO OTHER DIAGNOSIS PROCEDURE (Power Seat Position is not Memorized)

OK

5.

REPLACE OUTER MIRROR CONTROL ECU ASSEMBLY LH

(a) Replace the outer mirror control ECU assembly LH with a new or known good one.

Click here 2019 - 2022 MY Avalon Avalon HV [04/2018 -        ]; MIRROR (EXT): OUTER MIRROR CONTROL ECU: REMOVAL

NEXT

6.

CHECK SEAT POSITION MEMORY AND RESTORING FUNCTION

(a) Check the seat position memory and restoring functions.

Click here 2019 - 2022 MY Avalon [04/2018 -        ]; SEAT: FRONT POWER SEAT CONTROL SYSTEM (for Gasoline Model with Memory): OPERATION CHECK

OK:

Seat position memory and restoring functions operate normally.

OK

END (OUTER MIRROR CONTROL ECU ASSEMBLY LH WAS DEFECTIVE)
NG

GO TO STEP 8

7.

READ VALUE USING TECHSTREAM (SHIFT P POSITION STATE)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List.

(e) Read the Data List according to the display on the Techstream.

Powertrain > Engine > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Shift SW Status (P Range)

Park/neutral position switch status

ON or OFF

ON: Shift lever in P

OFF: Shift lever not in P

-

Powertrain > Engine > Data List

Tester Display

Shift SW Status (P Range)

OK:

On the Techstream screen, ON or OFF is displayed accordingly.

NG

GO TO AUTOMATIC TRANSAXLE SYSTEM (P070513)

UA80E: Click here 2019 - 2022 MY Avalon [04/2018 -        ]; UA80E (AUTOMATIC TRANSMISSION / TRANSAXLE): AUTOMATIC TRANSAXLE SYSTEM: P070513,P070562; Transmission Range Sensor "A" Circuit Open

UB80F: Click here 2021 - 2022 MY Avalon [08/2020 -        ]; UB80F (AUTOMATIC TRANSMISSION / TRANSAXLE): AUTOMATIC TRANSAXLE SYSTEM: P070513,P070562; Transmission Range Sensor "A" Circuit Open

OK

8.

REPLACE POSITION CONTROL ECU ASSEMBLY

(a) Replace the position control ECU assembly with a new or known good one.

Click here 2019 - 2021 MY Avalon Avalon HV [04/2018 - 08/2021]; SEAT: POWER SEAT CONTROL ECU: REMOVAL 2022 MY Avalon Avalon HV [08/2021 -        ]; SEAT: POWER SEAT CONTROL ECU: REMOVAL

NEXT

9.

CHECK SEAT POSITION MEMORY AND RESTORING FUNCTION

(a) Check the seat position memory and restoring functions.

Click here 2019 - 2022 MY Avalon [04/2018 -        ]; SEAT: FRONT POWER SEAT CONTROL SYSTEM (for Gasoline Model with Memory): OPERATION CHECK

OK:

Seat position memory and restoring functions operate normally.

OK

END (POSITION CONTROL ECU ASSEMBLY WAS DEFECTIVE)
NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) 2019 - 2021 MY Avalon Avalon HV [04/2018 - 08/2021]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL 2022 MY Avalon Avalon HV [08/2021 -        ]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL

10.

READ VALUE USING TECHSTREAM (DRIVER DOOR COURTESY SWITCH)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Main Body / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Main Body > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

FL Door Courtesy SW

Front door courtesy light switch assembly (driver door) signal

ON or OFF

ON: Driver door open

OFF: Driver door closed

-

Body Electrical > Main Body > Data List

Tester Display

FL Door Courtesy SW

OK:

On the Techstream screen, ON or OFF is displayed accordingly.

OK

REPLACE POSITION CONTROL ECU ASSEMBLY 2019 - 2021 MY Avalon Avalon HV [04/2018 - 08/2021]; SEAT: POWER SEAT CONTROL ECU: REMOVAL 2022 MY Avalon Avalon HV [08/2021 -        ]; SEAT: POWER SEAT CONTROL ECU: REMOVAL

NG

GO TO LIGHTING SYSTEM (Front Door Courtesy Switch Circuit)