Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual: One or more Power Seat Motors do not Operate

Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual / Vehicle Interior / Seat / Front Power Seat Control System (w/ Memory) / One or more Power Seat Motors do not Operate

DESCRIPTION

Signals are input into the position control ECU and switch assembly LH. The built-in ECU manages the signals received from the position control ECU and switch assembly LH, and operates each motor. If the position control ECU and switch assembly LH receives more than 2 motor operation signals for the same motor, the motor will be stopped. Manual operation is restarted when the position control ECU and switch assembly LH receives 1 signal only.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CHECK FRONT POWER SEAT OPERATION

(a) Check that each function of the power seat operates normally by using the position control ECU and switch assembly LH.

Click here

Result

Proceed to

One or more power seat functions (except lumbar support adjustment function) do not operate

A

All power seat functions do not operate

B

Front vertical and lifter functions do not operate

C

Only lumbar support adjustment function does not operate

D
B

GO TO OTHER DIAGNOSIS PROCEDURE (Front Power Seat does not Operate with Front Power Seat Switch)

C

GO TO STEP 7

D

GO TO STEP 8

A

2.

READ VALUE USING TECHSTREAM (POWER SEAT 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 / 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

Reclining Rear

Reclining switch signal (Rearward)

ON or OFF

ON: Reclining switch (Rearward) on

OFF: Reclining switch (Rearward) off

-

Reclining Front

Reclining switch signal (Forward)

ON or OFF

ON: Reclining switch (Forward) on

OFF: Reclining switch (Forward) off

-

Front Vertical Down

Front vertical switch signal (Downward)

ON or OFF

ON: Front vertical switch (Downward) on

OFF: Front vertical switch (Downward) off

-

Front Vertical Up

Front vertical switch signal (Upward)

ON or OFF

ON: Front vertical switch (Upward) on

OFF: Front vertical switch (Upward) off

-

Lifter Switch Down

Lifter switch signal (Downward)

ON or OFF

ON: Lifter switch (Downward) on

OFF: Lifter switch (Downward) off

-

Lifter Switch Up

Lifter switch signal (Upward)

ON or OFF

ON: Lifter switch (Upward) on

OFF: Lifter switch (Upward) off

-

Slide Rear

Slide switch signal (Rearward)

ON or OFF

ON: Slide switch (Rearward) on

OFF: Slide switch (Rearward) off

-

Slide Front

Slide switch signal (Forward)

ON or OFF

ON: Slide switch (Forward) on

OFF: Slide switch (Forward) off

-
Body Electrical > Driver Seat > Data List

Tester Display

Reclining Rear

Reclining Front

Front Vertical Down

Front Vertical Up

Lifter Switch Down

Lifter Switch Up

Slide Rear

Slide Front

OK:

On the Techstream screen, ON or OFF is displayed accordingly

NG

GO TO STEP 6

OK

3.

PERFORM ACTIVE TEST USING TECHSTREAM (POWER SEAT MOTOR)

(a) Enter the following menus: Body Electrical / Driver Seat / Active Test.

(b) Perform the Active Test according to the display on the Techstream.

Body Electrical > Driver Seat > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Seat Reclining

Seat reclining operation

OFF/Rear/Front

-

Front Vertical Operation

Seat front vertical operation

OFF/Down/Up

-

Lifter Operation

Seat lifter operation

OFF/Down/Up

-

Seat Slide Operation

Seat slide operation

OFF/Rear/Front

-
Body Electrical > Driver Seat > Active Test

Tester Display

Seat Reclining
Body Electrical > Driver Seat > Active Test

Tester Display

Front Vertical Operation
Body Electrical > Driver Seat > Active Test

Tester Display

Lifter Operation
Body Electrical > Driver Seat > Active Test

Tester Display

Seat Slide Operation

Result

Proceed to

The power seat functions operate normally.

A

Slide, front vertical or lifter function does not operate normally.

B

Reclining function does not operate normally.

C
A

REPLACE POSITION CONTROL ECU AND SWITCH ASSEMBLY LH

C

GO TO STEP 5

B

4.

INSPECT FRONT SEAT ADJUSTER ASSEMBLY LH

HINT:

Check the operation of the motor of the function that did not operate normally.

(a) Remove the front seat adjuster assembly LH.

Click here

(b) Inspect the front seat adjuster assembly LH (slide motor, front vertical motor or lifter motor).

Click here

OK

GO TO STEP 6

NG

REPLACE FRONT SEAT ADJUSTER ASSEMBLY LH

5.

INSPECT FRONT SEATBACK FRAME SUB-ASSEMBLY LH

(a) Remove the front seatback frame sub-assembly LH.

Click here

(b) Inspect the front seatback frame sub-assembly LH (reclining motor).

Click here

NG

REPLACE FRONT SEATBACK FRAME SUB-ASSEMBLY LH

OK

6.

CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU AND SWITCH ASSEMBLY LH - POWER SEAT MOTOR)

(a) Disconnect the c5 position control ECU and switch assembly LH connector.

(b) Measure the resistance according to the value(s) in the table below.

HINT:

Check the wire harness and connector between the position control ECU and switch assembly LH and applicable motor.

Standard Resistance:

Tester Connection

Condition

Specified Condition

c5-3 (SLD+) - c1-4

Always

Below 1 Ω

c5-3 (SLD+) or c1-4 - Body ground

Always

10 kΩ or higher

c5-4 (SLD-) - c1-1

Always

Below 1 Ω

c5-4 (SLD-) or c1-1 - Body ground

Always

10 kΩ or higher

c5-5 (FRV-) - c2-1

Always

Below 1 Ω

c5-5 (FRV-) or c2-1 - Body ground

Always

10 kΩ or higher

c5-8 (FRV+) - c2-2

Always

Below 1 Ω

c5-8 (FRV+) or c2-2 - Body ground

Always

10 kΩ or higher

c5-10 (LFT+) - c3-2

Always

Below 1 Ω

c5-10 (LFT+) or c3-2 - Body ground

Always

10 kΩ or higher

c5-12 (LFT-) - c3-1

Always

Below 1 Ω

c5-12 (LFT-) or c3-1 - Body ground

Always

10 kΩ or higher

c5-9 (RCL+) - e2-2

Always

Below 1 Ω

c5-9 (RCL+) or e2-2 - Body ground

Always

10 kΩ or higher

c5-11 (RCL-) - e2-1

Always

Below 1 Ω

c5-11 (RCL-) or e2-1 - Body ground

Always

10 kΩ or higher
OK

REPLACE POSITION CONTROL ECU AND SWITCH ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.

CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU AND SWITCH ASSEMBLY LH - BATTERY)

(a) Disconnect the c6 position control ECU and switch assembly LH connector.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

c6-12 (SYSB) - Body ground

Always

11 to 14 V
OK

REPLACE POSITION CONTROL ECU AND SWITCH ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.

INSPECT FRONT LUMBAR POWER SEAT SWITCH (DRIVER SEAT)

(a) Remove the front lumbar power seat switch (driver seat).

Click here

(b) Inspect the front lumbar power seat switch (driver seat).

Click here

NG

REPLACE FRONT LUMBAR POWER SEAT SWITCH (DRIVER SEAT)

OK

9.

INSPECT LUMBAR SUPPORT ADJUSTER ASSEMBLY LH

(a) Remove the lumbar support adjuster assembly LH.

Click here

(b) Inspect the lumbar support adjuster assembly LH.

Click here

NG

REPLACE LUMBAR SUPPORT ADJUSTER ASSEMBLY LH

OK

10.

CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU AND SWITCH ASSEMBLY LH - FRONT LUMBAR POWER SEAT SWITCH (DRIVER SEAT))

(a) Disconnect the c5 position control ECU and switch assembly LH connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

c5-6 (+B2) - c7-5 (B)

Always

Below 1 Ω

c5-6 (+B2) or c7-5 (B) - Body ground

Always

10 kΩ or higher

c5-1 (GND2) - c7-2 (E)

Always

Below 1 Ω

c5-1 (GND2) or c7-2 (E) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

11.

CHECK HARNESS AND CONNECTOR (FRONT LUMBAR POWER SEAT SWITCH (DRIVER SEAT) - LUMBAR SUPPORT ADJUSTER ASSEMBLY LH)

(a) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

c7-3 (H) - e3-1

Always

Below 1 Ω

c7-3 (H) or e3-1 - Body ground

Always

10 kΩ or higher

c7-1 (R) - e3-2

Always

Below 1 Ω

c7-1 (R) or e3-2 - Body ground

Always

10 kΩ or higher

c7-3 (H) - e3-1*

Always

Below 1 Ω

c7-3 (H) or e3-1 - Body ground*

Always

10 kΩ or higher

c7-1 (R) - e3-2*

Always

Below 1 Ω

c7-1 (R) or e3-2 - Body ground*

Always

10 kΩ or higher

c7-4 (U) - e4-1*

Always

Below 1 Ω

c7-4 (U) or e4-1 - Body ground*

Always

10 kΩ or higher

c7-6 (D) - e4-2*

Always

Below 1 Ω

c7-6 (D) or e4-2 - Body ground*

Always

10 kΩ or higher
  • *: w/ Seat Variable Cushion Switch
OK

REPLACE POSITION CONTROL ECU AND SWITCH ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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