Lexus NX: Power Seat does not Return to Memorized Position

Lexus NX Service Manual / Vehicle Interior / Seat / Front Power Seat Control System (w/ Memory) / Power Seat does not Return to Memorized Position

DESCRIPTION

When either the M1, M2 or M3 switch is pressed, the outer mirror control ECU assembly (for Driver Side) 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 front power seat switch LH. The front power seat switch LH operates each motor to achieve each memorized position value.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

    Click here

  • 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 switches. The seat memory function does 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 switches. The seat memory restoring function does not operate unless the switches are released.

  • Before replacing the main body ECU (multiplex network body ECU), refer to the Smart Access System with Push-button Start (for Entry Function).

    Click here

PROCEDURE

1.

CHECK FRONT POWER SEAT OPERATION

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

Click here

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 that the seat position memory function.

Click here

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, M2 or M3 switch.

Click here

  • The power switch is on (IG), and the shift lever is in P.*1
  • The power switch is turned off within 180 seconds after the driver door is closed and opened.*2
  • The power switch is turned off within 60 seconds after the driver door is opened and closed.*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 8

A

4.

READ VALUE USING TECHSTREAM (SEAT MEMORY NO1, SEAT MEMORY NO2, SEAT MEMORY NO3)

(a) Store a seat position in memory for each of the M1, M2 and M3 switches.

Click here

(b) Connect the Techstream to the DLC3.

(c) Turn the power 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

-

Seat Memory No3

Seat position memorized with M3 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

Seat Memory No3

OK:

Mem appears on the Techstream screen.

NG

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

OK

5.

REPLACE OUTER MIRROR CONTROL ECU ASSEMBLY (for Driver Side)

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

Click here

NEXT

6.

CHECK SEAT POSITION MEMORY AND RESTORING FUNCTION

(a) Check that the seat position memory and restoring function.

Click here

OK:

Seat position memory and restoring function operates normally.

OK

END (OUTER MIRROR CONTROL ECU ASSEMBLY [for Driver Side] WAS DEFECTIVE)

NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

7.

READ VALUE USING TECHSTREAM (P SWITCH)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

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

(e) 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

P Switch

Park state signal

ON or OFF

ON: Shift lever in P

OFF: Shift lever in a position other than P

-

Body Electrical > Driver Seat > Data List

Tester Display

P Switch

OK:

The Techstream display changes correctly in response to the switch operation.

OK

REPLACE FRONT POWER SEAT SWITCH LH

NG

GO TO HYBRID CONTROL SYSTEM

8.

READ VALUE USING TECHSTREAM (FL DOOR COURTESY SW)

(a) Connect the Techstream to the DLC3.

(b) Turn the power 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 LH 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:

The Techstream display changes correctly in response to the switch operation.

OK

REPLACE FRONT POWER SEAT SWITCH LH

NG

GO TO LIGHTING SYSTEM (Door Courtesy Switch Circuit)

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