2001 TOYOTA SEQUOIA relay

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

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.

DIDCZ±01
DI±716
± DIAGNOSTICSAIR SUSPENSION SYSTEM
910 Author: Date:
2005 SEQUOIA (RM1146U)
PROBLEM SYMPTOMS TABLE
HINT:

If a normal system code is displayed during the DTC check but the problem still occurs, check the cir-
cuits for each problem symptom in the order given in the table below and proceed to the relevant trou-
bleshooting page.

Inspect the fuse before inspecting the suspected areas as shown in the chart below.

Inspect each malfunction circuit in numerical order for the corresponding symptom.

If the malfunction still exists even after checking and confirming that all the circuits are normal, replace
the suspension control ECU.
SymptomSuspected AreaSee page
Vehicle height control function does not operate.
If the compressor remains on for an excessive period of
time or turns on and off repeatedly, the system control will
be halted for up to 70 minutes, after which the system will
return to normal operation.
1. Air tube is seized
2. Power source circuit
3. IG signal circuit
4. Crankshaft position sensor circuit
5. Height control mode select switch circuit
6. Height control switch circuit
7. Height control sensor circuit
8. Leveling solenoid valve circuit
9. Gate solenoid valve circuit
10.Exhaust solenoid valve circuit
11. AIR SUS relay circuit
12.Height control compressor circuit
13.Suspension control ECU
±
DI±761
DI±793
DI±210
DI±778
DI±774
DI±731
DI±740
DI±736
DI±744
DI±747
DI±752
IN±35
Illuminated position of height control indicator lamp does not
change by the height control switch operation.
1. Power source circuit
2. Crankshaft position sensor circuit
3. Height control mode select switch circuit
4. Height control switch circuit
5. Height control sensor circuit
6. Leveling solenoid valve circuit
7. Gate solenoid valve circuit
8. Exhaust solenoid valve circuit
9. AIR SUS relay circuit
10.Height control compressor circuit
11. Speed sensor circuit
12.CAN communication circuit
13.Suspension control ECUDI±763
DI±761
DI±793
DI±210
DI±778
DI±774
DI±731
DI±740
DI±736
DI±744
DI±783
DI±1065
IN±35
Hunting of vehicle height occurs.
1. Air leakage (Height control cylinder assy rear)
2. Height control sensor circuit
3. Suspension control ECUSA±156
DI±731
IN±35
Vehicle height control operates, but vehicle height is uneven.
1. Air leakage
2. Clogging of the air tube
3. Height control sensor link sub±assy
4. Height control sensor circuit
5. Gate solenoid valve circuit
6. Suspension control ECUSA±156
±
SA±156
DI±731
DI±736
IN±35
Vehicle height control operates, but vehicle height is high or
low (Vehicle height in NORMAL mode differs from the standard
value).1. Height control sensor link sub±assy
2. Height control sensor circuit
3. Suspension control ECUSA±156
DI±731
IN±35
When vehicle height control is adjusted, it stops at extremely high
or low position.1. Height control sensor circuit
2. Height control sensor link sub±assy
3. Suspension control ECUDI±731
SA±156
IN±35

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±717
911 Author: Date:
2005 SEQUOIA (RM1146U) Height control manual indicator lamp condition is abnormal.
1. Power source circuit
2. Height control mode select switch circuit
3. Height control manual indicator lamp circuit
4. Suspension control ECUDI±763
DI±778
DI±789
IN±35
Height control indicator lamp condition is abnormal.
1. Power source circuit
2. Height control indicator lamp circuit
3. Suspension control ECUDI±763
DI±785
IN±35
DTC check cannot be completed.
1. Power source circuit
2. CAN communication system
3. Height control manual indicator lamp circuit
4. Suspension control ECU
5. ECMDI±763
DI±782
DI±789
IN±35
IN±35
Input signal check (test mode) cannot be completed.
1. Power source circuit
2. CAN communication system
3. Suspension control ECU
4. Translate ECUDI±763
DI±783
IN±35
IN±35
Vehicle height is extremely low when vehicle is parked.
Although, especially in a cold district, the vehicle height
may become lower due to a drop in air temperature in the
height control cylinder assy, but this is not abnormal.
1. Air leakage
2. Height control cylinder assy
3. Height control sensor link sub±assy
4. Leveling solenoid valve circuit
5. Exhaust valve circuit
SA±156
±
SA±156
DI±740
DI±744
Compressor motor continues to operate.
Due to the air tube freezing, vehicle height may not rise.
1. Air leakage
2. Air tube clogged
3. Height control cylinder assy
4. Height control sensor link sub±assy
5. Height control sensor circuit
6. Leveling solenoid valve circuit
7. Exhaust valve circuit
8. AIR SUS relay circuit
9. Height control compressor circuit
10.Suspension control ECU
SA±156
±
±
SA±156
DI±731
DI±740
DI±744
DI±747
DI±752
IN±35

DIDD3±01
F16803
S25
DI±718
± DIAGNOSTICSAIR SUSPENSION SYSTEM
912 Author: Date:
2005 SEQUOIA (RM1146U)
TERMINALS OF ECU
Symbols (Terminal No.)Wiring ColorTerminal
DescriptionConditionSpecified Condition
SLEX (S25±1) ± LR WB
Exhaust Sole-
id V l Si
IG switch ON "
E i idli b tt f h i ht t l it h i h dBelow 1.0 V "SLEX (S25 1)
GND (S25±22)L±R ± W±Bnoid Valve Sig-
nalEngine idling, button of height control switch is pushed
from ºUPº to ºDOWNºBelow 1.0 V "
9 V or more
SLRR (S25±3) ± LG R W B
Leveling Sole-
id V l Si
IG switch ON "
E i idli b tt f h i ht t l it h i h dBelow 1.0 V "SLRR (S25 3)
GND (S25±22)LG±R ± W±Bnoid Valve Sig-
nalEngine idling, button of height control switch is pushed
from ºDOWNº to ºUPºBelow 1.0 V "
9 V or more
SLRL (S25±4) ± WL WBGate SolenoidIG switch ON "
E i idli b tt f h i ht t l it h i h dBelow 1.0 V "SLRL (S25 4)
GND (S25±22)W±L ± W±BGate Solenoid
Valve SignalEngine idling, button of height control switch is pushed
from ºDOWNº to ºUPºBelow 1.0 V "
9 V or more
RC (S25±5) ± GY WBAIR SUS RelayIG switch ON "
E i idli b tt f h i ht t l it h i h dBelow 1.0 V "RC (S25 5)
GND (S25±22)G±Y ± W±BAIR SUS Relay
SignalEngine idling, button of height control switch is pushed
from ºNº to ºUPºBelow 1.0 V "
9 V or more
HI (S25±8) ± GR R W B
Height Control
I di t ºHIº
Engine idling, vehicle height is ºNORMALº "
P i th ºUPº b tt f th t l it h t10 V or more "HI (S25 8)
GND (S25±22)GR±R ± W±BIndicator ºHIº
SignalPressing the ºUPº button of the control switch turns on
the ºHIº indicator lamp (*1)10 V or more "
Below 5 V
NR (S25±9) ± BL WB
Height Control
I di t ºNº
Engine idling, vehicle height is ºNORMALº "
P i th ºUPº b tt f th t l it h tBelow 5 V "NR (S25 9)
GND (S25±22)B±L ± W±BIndicator ºNº
SignalPressing the ºUPº button of the control switch turns on
the ºHIº indicator lamp (*1)Below 5 V "
10 V or more
IG (S25±10) ±
GND (S25±22)B±R ± W±BIgnition SwitchIG switch ON10 to 14 V
VN (S25±11) ± LG W B
Height Control
MlIdi
IG switch ON, height control manual indicator lamp ON
" Pressin
g and releasing the height control mode selectBelow 5 V "VN (S25 11)
GND (S25±22)LG ± W±BManual Indica-
tor Lamp Signal" Pressing and releasing the height control mode select
switch turns off the height control manual indicator lamp
(*1)
Below 5 V "
10 V or more
TD (S25±12) ± BR B W B
Height Control
Md Sl t
IG switch ON, height control mode select switch pushed
iBelow 1.5 V "TD (S25 12)
GND (S25±22)BR±B ± W±BMode Select
Switchin
" Height control select switch releasedBelow 1.5 V "
10 to 14 V
UPSW (S25±13) ± LB WB
Height Control
S it h ºUPº
IG switch ON, ºUPº button of height control switch
hdiBelow 1.5 V "UPSW (S25 13)
GND (S25±22)L±B ± W±BSwitch ºUPº
Signalpushed in "
ºUPº button of height control switch releasedBelow 1.5 V "
10 to 14 V
SBL (S25±15) ±
SGL (S25±19)G±O ± L±R
Height Control
Sensor Power
Source
IG switch ON4.5 to 5.5 V
SHRL (S25±17) ± GR L L R
Height Control
SIt
IG switch ON "
E i idli hi l h i ht i h d f ºHIGHº t0.5 to 4.5 V "SHRL (S25 17)
SGL (S25±19)GR±L ± L±RSensor Input
SignalEngine idling, vehicle height is changed from ºHIGHº to
ºNORMALº by pressing the height control switch0.5 to 4.5 V "
Approx. 2.5 V
SGL (S25±19) ±
GND (S25±22)L±R ± W±BHeight Control
Sensor GroundAlwaysBelow 1.0 V

DIDDC±01
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±725
919 Author: Date:
2005 SEQUOIA (RM1146U)
FAIL±SAFE CHART
FAIL±SAFE FUNCTION
When a rear air suspension system malfunction is detected under normal control operation, the suspension
control ECU will suspend the switch control of the height control operation.
FAIL±SAFE CHART
DTC No.Malfunction ItemFail±safe OperationFail±safe Deactivation
Condition
C1714/14Malfunction in height
control sensor
Auto mode:
When the target vehicle height, just before fail, is higher than
ºNº, vehicle height is lowered for 20 seconds and then sys-
tem control shuts down.
Manual mode:
When the target vehicle height, just before switching to the
manual mode, is higher than ºNº, the switch operation to
lower vehicle height is available for only 20 seconds.
Return to normal condition.
C1733/33Open or short in gate
solenoid valveSystem control shuts down.Return to normal condition.
C1734/34Open or short in level-
ing solenoid valveSystem control shuts down.Return to normal condition.
C1735/35Open or short in ex-
haust solenoid valve
Auto mode:
After vehicle height is raised through control, the system
shuts down.
Manual mode:
When vehicle height is lower than ºNº, only the switch opera-
tion to raise vehicle height is available.
Return to normal condition.
C1741/41Open or short in AIR
SUS relay circuit
Auto mode:
After vehicle height is lowered through control, the system
shuts down.
Manual mode:
When vehicle height is higher than ºNº, only the switch op-
eration to lower vehicle height is available.
Return to normal condition.
C1742/42Lock in height control
compressor motor
Auto mode:
After vehicle height is lowered through control, the system
shuts down.
Manual mode:
When vehicle height is higher than ºNº, only the switch op-
eration to lower vehicle height is available.
After interrupting for 70 min-
utes, restart the control.
C1751/51
Powered continuously
or powered excessive-
ly in height control
compressor motor
Auto mode:
After vehicle height is lowered through control, the system
shuts down.
Manual mode:
When vehicle height is higher than ºNº, only the switch op-
eration to lower vehicle height is available.
After interrupting for 70 min-
utes, restart the control.
C1761/61Malfunction in suspen-
sion control ECUSystem control shuts down.Return to normal condition.
C1774/74Power voltage
droppedSystem control shuts down.Return to normal condition.
U0100/65Lost communication
with TL ECUSystem control continues.Return to normal condition.