2001 TOYOTA SEQUOIA ECU

D14217
ECM
L4 E6
F2324
IG410
L±R* L±R* 4WD Control ECU
*: 4WD L413 DI±686
± DIAGNOSTICSAUTOMATIC TRANSMISSION
880 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL MALFUNCTION THRESHOLDS
Detection criteriaThreshold
Both of the following conditions is met: ON malfunctions (A) and (B)
ON malfunction (A)
L4 switchON
ON malfunction (B)
Actual Transfer gear ratio
Transfer input speed/Transfer output speed0.9 to 1.1
WIRING DIAGRAM

D14237L4
4WD Control ECU: F23
D14167
ECM:
E8E7E6E5E4
L4(+)
± DIAGNOSTICSAUTOMATIC TRANSMISSION
DI±687
881 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
1 Inspect terminal voltage (L4 ± body ground).
PREPARATION:
Disconnect the 4WD control ECU connector and turn the igni-
tion switch ON.
CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:
Tester ConnectionSpecified Condition
F23 ± 24 (L4) ± Body ground10 to 14 V
NG Check and replace 4WD control ECU
(See page TR±39).
OK
2 Inspect terminal voltage (L4 ± body ground).
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:
Tester ConnectionSpecified Condition
E6 ± 13 (L4) ± Body ground10 to 14 V
NG Replace the ECM (See page SF±80).
OK
Repair or replace the harness or connector
(See page IN±35).

DIDCF±01
F19439
Crankshaft
Position SensorEngine Room R/B No. 3
Engine Room J/B
Instrument
Panel J/B

STOP Fuse

IGN1 Fuse

ECU±IG Fuse
Stop Light
Switch
Combination Meter
Height Control Switch Body ECU
ECM Engine Room R/B No. 2
Suspension Control ECU
Translate ECU
4LO Switch
2WD/4HI Switch
Height Control Mode Select SwitchIgnition Switch
Height Control Indicator
Fusible Link Block

AIR SUS Fuse

AM2 Fuse

Height Control Manual IndicatorCenter Diff. Lock Switch
DLC3
Vehicle Speed Sensor
Vehicle Speed Sensor

AIR SUS Relay

AIR SUS No. 2 Fuse DI±696
± DIAGNOSTICSAIR SUSPENSION SYSTEM
890 Author: Date:
2005 SEQUOIA (RM1146U)
LOCATION

DIDCI±01
F19438
Height Control Sensor
Sub±assy
Height Control Mode
Select Switch
Body ECU
Stop Light Switch
Front Door Courtesy
Light Switch (Driver)
Front Door Courtesy
Light Switch
(Passenger)
Rear Door Courtesy
Light Switch (LH)
Rear Door Courtesy
Light Switch (RH)
Back Door Courtesy
Light SwitchCombination Meter
Leveling Solenoid Valve
AIR SUS Relay
DLC3
ECM
Translate ECU Compressor/
Height Control Dryer
Exhaust Solenoid Valve Height Control Valve
Compressor Assy Gate Solenoid Valve IG
BBAT
SBL2
SHRL
SGL2VN
HI
NR
LO
TD
UPSW
DWSW
Door
STPSLRR
SLRL
RC
RM+
RM±
SLEX
SIL
CANH
CANL
CANSuspension
Control ECU Height Control Switch
GND From IG SwitchFrom Battery
From
Battery DI±698
± DIAGNOSTICSAIR SUSPENSION SYSTEM
892 Author: Date:
2005 SEQUOIA (RM1146U)
SYSTEM DIAGRAM

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±699
893 Author: Date:
2005 SEQUOIA (RM1146U)
Input and output signals of each ECU.
Transmitting ECUReceiving ECUSignalCommunication method
ECM

Translate ECU

Suspension control
ECU

Engine speed signal

Transmission signal

Shift position signal

L4 switch signal

TC signal
CAN
Translate ECUSuspension control
ECU
Vehicle wheel speed signal

TS signalCAN
Suspension control ECUTranslate ECUAir suspension setting signalCAN

DIDCN±01
F19465
: CAN
Compressor Assy
Combination Meter
Suspension
Control
ECU Exhaust Solenoid
Valve
Gate Solenoid Valve
Leveling Solenoid ValveAIR SUS Relay
Height Control Cylinder
(Pneumatic Cylinder)
Height Control Sensor
Sub±assy : ECU Output Signal
: ECU Input Signal
: Air Flow Path
Dryer
Height Control Cylinder
(Pneumatic Cylinder)
Speed Sensors

Engine Speed

L4 Switch

Shift Position
Information

Transmission
Model Informa-
tion

Height Control Mode Select
Switch

Height Control Switch

Courtesy Light Switches

Stop Light SwitchHI
N
LO
MAN. DI±700
± DIAGNOSTICSAIR SUSPENSION SYSTEM
894 Author: Date:
2005 SEQUOIA (RM1146U)
SYSTEM DESCRIPTION
1. GENERAL
This system uses pneumatic cylinders instead of the coil springs that are used in a conventional rear
suspension. The suspension control ECU analyzes the information based on the switches, sensors,
and input signals, operates the compressor assy, and uses the solenoid valves to control the vehicle
height.
The suspension control ECU detects, via the height control sensor, the changes in the rear vehicle
height that results from the number of occupants or the amount of the load. Then, the suspension con-
trol ECU controls the height control solenoid valves and the compressor assy in order to automatically
adjust the rear vehicle height to a constant (normal) vehicle height.
Furthermore, three vehicle heights can be selected by operating the height control switch: HI, NOR-
MAL, and LO. The HI vehicle height ensures the vehicle's drive±through performance on rough roads.
The LO vehicle height facilitates the entry and exit of the occupants and the loading and unloading
of cargo. The NORMAL vehicle height helps realize excellent controllability and riding comfort during
normal driving.

DI±702
± DIAGNOSTICSAIR SUSPENSION SYSTEM
896 Author: Date:
2005 SEQUOIA (RM1146U)
3. FUNCTION OF MAIN COMPONENTS
ComponentOutline
Height Control Mode Select SwitchUsed to select vehicle height control mode (Auto/Manual).
Used to operate or stop auto leveling control.
Height Control SwitchAuto mode: Used to select vehicle height (HIGH, NORMAL, LOW).
Manual mode: Used to select vehicle height optionally.
Height Control SensorConverts the vertical change of the rear axle, in proportion to the standard, to sig-
nals and detects vehicle height.
Height Control Indicator Lamp (Combination Meter)Auto mode: Target vehicle height is displayed (HIGH, NORMAL, LOW).
Manual mode: Current vehicle height is displayed (HIGH, NORMAL, LOW).
Height Control Manual Indicator Lamp (Combination Meter)
Comes on during manual mode.
Blinks when the suspension control ECU detects a system malfunction.
Blinks during test mode.
Displays output DTC.
Stop light SwitchDetects braking condition.
Used to clear DTCs.
Pneumatic Cylinder (Height Control Cylinder Assy)Supports the vehicle body and adjusts the vehicle height.
Height Control Compressor Assy (Compressor/Height Con-
trol Dryer)The compressor generates compressed air that is necessary to raise vehicle
height and supplies it to the height control cylinder assy.
The dryer removes moisture from the compressed air.
Exhaust Solenoid ValveDrains the air in the height control cylinder assy when vehicle height is lowered.
(Built into the height control compressor assy)
Leveling Solenoid ValveOpens or closes the passage between the height cylinder assy and height control
compressor assy.
Gate Solenoid ValveOpens or closes the passage between the right and left height control cylinder assy
(Built into the leveling solenoid valve).
Suspension Control ECU
Estimates vehicle condition based on the signals from sensors and switches, and
outputs the control signals to the compressor and valves.
Blinks the height control manual indicator light when a system malfunction is de-
tected.
Air Suspension RelaySupplies power to the height control compressor assy.
Door Courtesy Switch (Body ECU)Detects whether the 5 doors, including the back door, are opened or closed, and
sends the signals to the suspension control ECU.
ECMSends the engine speed signal, etc. to the suspension control ECU through CAN
communication.
Speed Sensor (Skid Control ECU)Sends the vehicle wheel speed signal, etc. to the suspension control ECU through
CAN communication via the translate ECU.

F19470
Low
High
Link
Arm
DI±706
± DIAGNOSTICSAIR SUSPENSION SYSTEM
900 Author: Date:
2005 SEQUOIA (RM1146U)
Height Control Sensor
The height control sensor detects the vehicle height. One sensor is located in the center of the rear
frame, which is connected to the center of the rear axle via a link, in order to detect the vehicle height.
The sensor has an arm that moves along with the change in vehicle height, and the resultant change
in voltage enables the suspension control ECU to detect the vehicle height.
A semiconductor type sensor has been adopted to make it compact and heat±resistant.
HINT:
Refer to the following factors when adjusting the link of the height control sensor:
The vehicle height changes approximately 4 mm (0.16 in.) with each turn of the link.
The vehicle height changes approximately 2 mm (0.08 in.) by moving the link installation position by
1 mm (0.04 in.).