Toyota Sequoia (2005). Manual - part 427

DIDDZ–01

I28552

Position Control ECU
& Switch Assy

Park/Neutral
Position Switch

Combination 
Meter

Power Seat Motor 
Driver Side (Reclining)

Power Seat Motor
Driver Side (Slide)

Power Seat Motor
Driver Side (Front Vertical)

Power Seat Motor
Driver Side (Lifter)

Front Door Courtesy
Light Switch Assy

Seat Memory Switch

Lumbar
Support
Control
Motor

Lumbar Support
Control Switch

To Battery

To Battery

To Ignition Switch

ECU–B

PWR SEAT

ECU–IG

SYSB

IG

+B

RCL+

RCL–

LFT+

LFT–

FRV+

FRV–

SLD+

SLD–

SW1

SW2

MMRY

DCTY

Key Unlock 
Warning Switch

KSW

Body ECU

BEAN

To Ignition Switch

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM (w/ Driving Position 
Memory)

DI–1503

1697

SYSTEM DIAGRAM

DIDE0–01

DI–1504

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM (w/ Driving Position 
Memory)

1698

SYSTEM DESCRIPTION

The power seat control system (w/ memory) is equipped with the following functions:

Manual operation of the driver side seat.

Individual seat positions for two different drivers can be stored for the slide–reclining front–verti-
cal 8–way lifter.

Similarly, power mirror positions for two different drivers can be stored. These are stored/restored
with the seat positions.

The above operations are performed using serial communication.

As a safety precaution, the system disallows seat position restoration unless the ignition switch
is ON, and the park/neutral position switch is in the P (park) position.

Manual adjustment of the slide reclining lumbar can be performed even when the ECU is not
functional.

When the power seat control switch is operated, a command signal is sent to the position control ECU. The
position control ECU then activates the appropriate seat motor as needed. This memory system does not
use a seat position sensor. The seat position is detected by counting pulses that are output when the motor
turns. If there is no pulse output from the motor, the motor will stop operating. The ECU is designed so that
a malfunction of the seat memory system will not interfere with manual seat control. The seat memory switch
also sends signals to the position control ECU to memorize a given seat position. The seat memory switch
is later used to send signals to the position control ECU to return to one of the memorized positions.

DIDE1–01

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM (w/ Driving Position 
Memory)

DI–1505

1699

HOW TO PROCEED WITH TROUBLESHOOTING

HINT:
Use this procedure to troubleshoot the front power seat control system with memory function.

1

Vehicle Brought To Workshop

NEXT

2

Customer Problem Analysis Check and Problem Symptom Check 
(See page 

DI–1507

)

NEXT

3

Problem Symptom Confirmation

Symptom Does Not Occur (Go to step 4)

Symptom Occurs (Go to step 5)

4

Symptom Simulation (See page 

IN–24

)

NEXT

5

Check Multiplex Communication System (See page 

DI–1904

)

Check if any DTCs are output.
HINT:
The position control ECU & switch assy of this system are connected to the multiplex communication system.
Therefore, before starting troubleshooting, make sure to check that there is no trouble in the multiplex com-
munication system.

Multiplex System DTC is Output (Proceed to
”Multiplex Communication System”)

No Multiplex System DTC (Go to step 6)

DI–1506

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM (w/ Driving Position 
Memory)

1700

6

Problem Symptoms Table (See page 

DI–1508

)

NEXT

7

Identification of Problem

NEXT

8

Adjustment, Repair or Replace

NEXT

9

Confirmation Test

NEXT

End