2001 TOYOTA SEQUOIA solenoid

± 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.

DIDDE±01
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±727
921 Author: Date:
2005 SEQUOIA (RM1146U)
DATA LIST / ACTIVE TEST
1. DATA LIST
HINT:
By accessing the DATA LIST displayed by the hand±held tester, you can read the value of the switches and
sensors and so on without removing any parts. Reading the DATA LIST is the first step of troubleshooting
and is one method to shorten labor time.
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Following the display on the tester, read the DATA LIST.
AIR SUSPENSION:
ItemMeasurement Item / Range (Dis-
play)Normal ConditionDiagnostic Note
VEHICLE SPD
Vehicle speed reading / min.: 0
km/h (0 mph), max.: 255 km/h
(158 mph)
Actual vehicle speedSpeed indicated on the combina-
tion meter
FR WHEEL SPD
Wheel speed (Front right) reading /
min.: 0 km/h (0 mph), max.: 255
km/h (159 mph)
Actual vehicle speedSpeed indicated on the speedome-
ter
FL WHEEL SPD
Wheel speed (Front left) reading /
min.: 0 km/h (0 mph), max.: 255
km/h (159 mph)
Actual vehicle speedSpeed indicated on the speedome-
ter
IG VOLTAGEECU power supply voltage / min.:
0 V, max.: 25.5 VActual ECU power supply voltage:
10 to 14 V±
POWER VOLTAGE+B power source voltage / min.: 0
V, max.: 25.5 VActual battery power supply volt-
age: 10 to 14 V±
STEERING ANG
Steering angle sensor reading /
min.: ±49150.5 deg, max.: 49152
degActual steering angle /
Left turn: reading increases
Right turn: reading increasesZero point is set at the point when
battery is connected
ENGINE SPDCrankshaft position sensor read-
ing / min.: 0 rpm, max.: 25,500 rpmActual engine speedSpeed indicated on the combina-
tion meter
HEIGHT SW DOWNHeight control switch (DOWN) /
ON or OFFON: Height control switch
ºDOWNº button pressed
OFF: ±
±
HEIGHT SW UPHeight control switch (UP) / ON or
OFFON: Height control switch ºUPº
button pressed
OFF: ±
±
HEIGHT SW HOLDHeight control mode select switch
/ ON or OFFON: Height control mode select
switch pressed
OFF: ±
±
STOP LIGHT SWStop light switch / ON or OFFON: Brake pedal depressed
OFF: Brake pedal released±
DOOR SWDoor courtesy light switch / ON or
OFFON: Open each door
OFF: Close all doors±
L4 SW4LO switch / ON or OFFON: 2WD/4HI switch pressed
OFF: ±±
TSTS terminal / ON or OFFON: During test mode
OFF: Normal mode±
TCTC terminal / ON or OFFON: DTC recorded
OFF: No DTC recorded±
SOL SLRLHeight control valve solenoid (Lev-
elling solenoid valve) / ON or OFFON: Leveling solenoid operated
OFF: Leveling solenoid not oper-
ated
±
SOL SLRGHeight control valve solenoid
(Gate solenoid valve) / ON or OFFON: Gate solenoid operated
OFF: Gate solenoid not operated±

DI±728
± DIAGNOSTICSAIR SUSPENSION SYSTEM
922 Author: Date:
2005 SEQUOIA (RM1146U) MAIN RELAY
MAIN relay / ON or OFFON: MAIN relay operated
OFF: MAIN relay not operated±
MOTOR RELAYAIR SUS relay / ON or OFFON: Compressor operated
OFF: Compressor not operated±
RR HEIGHT
Right rear height control sensor
reading / min.: ±3276.7 mm
(±129.004 in.), max.: 3276.8 mm
(129.008 in.)
Always: 0 mm (0 in.)±
RL HEIGHT
Left rear height control sensor
reading / min.: ±3276.7 mm
(±129.004 in.), max.: 3276.8 mm
(129.008 in.)
2WD:
Min.: ±15 mm (±0.59 in.)
Max.: 40 mm (1.57 in.)
4WD:
Min.: ±30 mm (±1.18 in.)
Max.: 40 mm (1.57 in.)
±
#CODESNumber of DTC recorded / min.: 0,
max.: 255Min.: 0, Max.: XX±
2. ACTIVE TEST LIST
HINT:
Perform the ACTIVE TEST using the hand±held tester to operate the sensors, relays and solenoids without
removing any parts. Performing the ACTIVE TEST is the first step of troubleshooting and is one of the meth-
ods to shorten labor time. It is possible to display the DATA LIST during the ACTIVE TEST.
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Following the display on the tester, perform the ACTIVE TEST.
AIR SUSPENSION:
ItemVehicle Condition / Test DetailsDiagnostic Note
RR HEIGHTTurn height control switch / UP or DOWN±
LEVEL SOL REARTurn leveling solenoid valve / ON or OFFOperation sound of solenoid (clicking sound) can
be heard
GATE SOL REARTurn gate solenoid valve / ON or OFFOperation sound of solenoid (clicking sound) can
be heard
MOTOR RELAYTurn AIR SUS relay / ON or OFFOperation sound of motor can be heard

DIDDG±01
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±729
923 Author: Date:
2005 SEQUOIA (RM1146U)
DIAGNOSTIC TROUBLE CODE CHART
HINT:

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

If no abnormality is found when the parts are inspected, inspect the suspension control ECU.

If a trouble code is displayed during the DTC check, check the circuit listed for that code. For details
of each code, refer to the ºSee pageº under respective DTC No. in the DTC chart.
DTC No.
(See Page)Detection ItemTrouble Area
Manual
Indicator
Lamp*
1Memory*2
C1714/14
(DI±731)Open or short in left rear height
control sensor circuit
Height control sensor sub±assy

Height control sensor circuit

Suspension control ECU

C1733/33
(DI±736)Open or short in gate solenoid
valve circuit
Gate solenoid valve (Height control valve)

Gate solenoid valve (Height control valve) circuit

Suspension control ECU

C1734/34
(DI±740)Open or short in leveling sole-
noid valve circuit
Leveling solenoid valve (Height control valve)

Leveling solenoid valve (Height control valve) circuit

Suspension control ECU

C1735/35
(DI±744)Open or short in exhaust sole-
noid valve circuit
Exhaust solenoid valve (Height control compressor)

Exhaust solenoid valve (Height control compressor) circuit

Suspension control ECU

C1741/41
(DI±747)Open or short in AIR SUS relay
circuit
AIR SUS relay

AIR SUS relay circuit

Suspension control ECU

C1742/42
(DI±752)Lock, open or short in height
control compressor circuit
Height control compressor assy

Height control compressor circuit

Suspension control ECU

C1751/51*3
(DI±757)
Continuous electric current to
height control compressor circuit

Height control compressor assy

Height control compressor circuit

Height control sensor circuit

Height control sensor sub±assy

Relief valve

AIR SUS relay circuit

Air leakage from the air tube or each valve

Clogging in the air tube or each valve

Suspension control ECU
X
C1761/61
(DI±761)ECU malfunction

Power source circuit

Suspension control ECU

Communication circuit
 / X
C1774/74
(DI±763)Power source drop

Battery

Power source circuit

Suspension control ECU
XX
U0100/65
(DI±782)Lost communication with ECM/
PCM
ECM

Suspension control ECU

Communication circuit
XX
U0122/67
(DI±783)Lost communication with TL
ECU
Translate ECU

Suspension control ECU

Communication circuit
XX
U0132/71
(DI±784)Lost communication with ride
level control module
Suspension control ECU

Communication circuitXX

F19442
Suspension Control ECU H16
Gate Solenoid Valve
(Height Control Valve)
W±L8
BM1SLRL 114
IN14
S25
BI W±B 2W±LW±L DI±736
± DIAGNOSTICSAIR SUSPENSION SYSTEM
930 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1733/33 Gate Solenoid Valve Circuit
CIRCUIT DESCRIPTION
The suspension control ECU opens the gate solenoid valve (height control valve) to lead the compressed
air to the height control cylinder (pneumatic cylinder) and to raise the vehicle height.
Further, the gate solenoid valve (height control valve) opens and closes the passage between the right and
left height control cylinders (pneumatic cylinders).
The height control valve consists of a leveling solenoid valve and a gate solenoid valve.
The gate solenoid valve opens and closes the passage between the compressor and the height control cylin-
der (pneumatic cylinder).
DTC No.DTC Detecting ConditionTrouble Area
C1733/33
Either of the following conditions is detected:
1. With the height control valve inactivated, an open signal of
the height control valve is detected for 1 sec. or more.
2. With the height control valve activated, a short signal of the
valve is detected 8 times successively.

Gate solenoid valve (Height control valve)

Gate solenoid valve (Height control valve) circuit

Suspension control ECU
HINT:

Once the ECU stores DTC C1733/33 in the memory, the vehicle height control is suspended until a
normal signal is input to the ECU from the height control solenoid valves. However, control is resumed
if the ignition switch is turned OFF, then ON again.

Malfunction in the gate solenoid valve:
The height control operation is suspended, and the height control indicator lamp does not change by
operating the height control switch.
WIRING DIAGRAM
DIDDN±01

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±737
931 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:

If DTC C1761/61 (ECU malfunction) and/or C1774/74 (power source circuit) is displayed, perform the
inspection necessary for DTC C1761/61 (See page DI±761) and/or C1774/74 (See page DI±763) first.
(If DTC C1761/61 and the C1774/74 are output at the same time, perform the inspection necessary
for DTC C1774/74 first.)

Start the inspection from step 1 when using the hand±held tester, and start from step 2 when not using
the hand±held tester.
1 Perform active test using hand±held tester.
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch ON, and push the hand±held tester main switch ON.
(c) Select the item ºGATE SOL REARº in the ACTIVE TEST, and operate it with the hand±held tester.
AIR SUSPENSION:
ItemVehicle Condition / Test DetailsDiagnostic Note
GATE SOL REARTurn gate solenoid valve / ON or OFFOperation sound of solenoid (clicking sound) can
be heard
CHECK:
(a) Check whether the solenoid makes sound.
(b) Check whether the height control valve has continuity (will vibrate).
OK:
The solenoid makes sound, and the height control valve has continuity (will vibrate).
RESULT:
NGA
OK (When troubleshooting according to the PROBLEM SYMPTOMS TABLE)B
OK (When troubleshooting according to the DTC chart)C
B Proceed to next circuit inspection shown in
problem symptoms table (See page DI±716).
C Replace suspension control ECU
(See page IN±35).
A