Page 956 of 4323
F19435
1 (+)
2 (±)
Connector Front View:
43
DI±754
± DIAGNOSTICSAIR SUSPENSION SYSTEM
948 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
1 Inspect height control compressor.
PREPARATION:
(a) Disconnect the height control compressor connector.
(b) Connect the positive (+) lead from the battery to terminal
1 and the negative (±) lead to terminal 2.
CHECK:
Apply battery voltage between terminals 1 and 2 of the height
control compressor.
OK:
Compressor motor operates.
NOTICE:
Do not operate the height control compressor assy
for 90 sec. or more.
Since a short and lock inside the height control com-
pressor assy causes enormous current to flow, stop
the operation immediately when it does not rotate.
CHECK:
Check continuity between each terminal of the height control
compressor.
OK:
Terminal No.Specified condition
2 ± 4Continuity
3 ± 4Continuity
NG Replace height control compressor
(See page SA±162).
OK
Page 958 of 4323
F19461
Height Control Compressor
Connector Front View:
H13
DI±756
± DIAGNOSTICSAIR SUSPENSION SYSTEM
950 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check harness and connector (Height control compressor ± Battery, Body
ground).
PREPARATION:
(a) Reconnect the ECU connector.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:
Tester connectionConditionSpecified value
H13±1 ± Body ground
Engine idling, height con-
trol switch is pushed from
ºNº to ºUPº
10 to 14 V
HINT:
Measure the voltage within 90 seconds.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Tester connectionConditionSpecified value
H13±2 ± Body groundAlwaysBelow 1 W
NG Repair or replace harness or connector.
OK
Replace suspension control ECU
(See page IN±35).
Page 961 of 4323

F19437
Height Control Valve
Connector Front View:
32 1
F19457
Height Control Compressor
Connector Front View:
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±759
953 Author: Date:
2005 SEQUOIA (RM1146U)
3 Inspect height control valve (Gate solenoid valve, Leveling solenoid valve) or
height control compressor (Exhaust solenoid valve).
When 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 ºLEVEL SOL REARº, ºGATE SOL REARº in the ACTIVE TEST, and operate it with the
hand±held tester.
AIR SUSPENSION:
ItemVehicle Condition / Test DetailsDiagnostic Note
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
HINT:
The exhaust solenoid valve cannot be tested in ACTIVE TEST.
CHECK:
(a) Check whether the solenoid makes a sound.
(b) Check whether the height control solenoid valve has continuity (will vibrate).
OK:
The solenoid makes a sound, and the height control solenoid valve has continuity. (It will vi-
brate.)
When not using hand±held tester:
PREPARATION:
Disconnect the valve connector.
CHECK:
Check the operating sound of the valves when battery positive
voltage is applied to the terminals as shown below.
Solenoid valveBattery positiveBattery negative
Height control valve
(Gate solenoid valve)12
Height control valve
(Leveling solenoid valve)32
Height control compressor
(Exhaust solenoid valve)12
OK:
It make an operating sound (click).
HINT:
When a malfunction is found in the gate solenoid valve,
replace the leveling valve and the height control valve.
When a malfunction is found in the exhaust solenoid
valve, replace the height control compressor assy.
Page 965 of 4323
F19445
Engine Room R/B No. 2
F10
Fusible Link BlockSuspension Control
ECU
AIR SUS No. 2
2
1
22 W
AIR SUS
9ALT
5B
Battery
IFJ12
J/C
AW±B22
S25
GND 24
S25
25
S25
BAT B J/C
B
J37
B
J37 C
J38 V
IA55
VV
V
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±763
957 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1774/74 Power Source Circuit
CIRCUIT DESCRIPTION
This circuit provides power to operate the suspension control ECU.
The suspension control ECU, controlling the air suspension system, is activated when the ignition
switch is turned ON. The main relay inside the ECU is activated after 2 seconds and the system is oper-
ated by +B power source.
DTC No.DTC Detecting ConditionTrouble Area
C1774/74The terminal B or BAT voltage is below 10 V or above 16 V for
0.5 seconds.Battery
Power source circuit
Suspension control ECU
WIRING DIAGRAM
DIDE3±01
Page 966 of 4323

DI±764
± DIAGNOSTICSAIR SUSPENSION SYSTEM
958 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
1 Inspect battery voltage.
CHECK:
Check the battery voltage.
OK:
Voltage: 11 to 14 V
NG Replace battery.
OK
HINT:
Start the inspection from step 2 when using the hand±held tester, and start from step 3 when not using the
hand±held tester.
2 Read value of the 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 ºPOWER VOLTAGEº in the DATA LIST, and read its value displayed on the hand±held
tester.
AIR SUSPENSION:
ItemMeasurement Item / Range (Dis-
play)Normal ConditionDiagnostic Note
POWER VOLTAGE+B power source voltage / min.: 0
V, max.: 25.5 VActual battery power supply volt-
age: 10 to 14 V±
CHECK:
Check the battery positive voltage.
OK:
Actual battery power supply voltage: 10 to 14 V
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 Check for intermittent problems.
HINT:
Check the connector and terminal (See page IN±24).
Page 969 of 4323
F19446
W
41G±Y1
4A11
4AG±Y27
S25 STP
BatteryB ALT
85 W 1
1L STOP 2
1FS14
Stop Light Switch
Sub J/B No. 4Suspension Control
ECU
Instrument Panel J/BF10
Fusible Link Block
1L
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±767
961 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1782/82 Stop Light Switch Circuit (Test Diagnosis)
CIRCUIT DESCRIPTION
When the brake pedal is depressed, the stop light comes on and the signal is input to the STP terminal of
the suspension control ECU.
HINT:
This DTC is output only when the sensor signal check is done.
DTC No.DTC Detecting ConditionTrouble Area
C1782/82The signal from the stop light switch assy does not change.
Stop light switch assy
Stop light switch circuit
Suspension control ECU
WIRING DIAGRAM
DIDE7±01
Page 987 of 4323
F19450
C6
Combination
MeterSuspension Control
ECU
I18
Ignition SW Instrument Panel J/B
Engine Room J/B24
14
15
16 LO
N
HIP
B±L
GR±R26
S25
9
S25
8
S25LO
NR
HI
6
IG2 AM25
W±R B±R IGN1 11
7 1H
1J1C
1C32
W±R
AM2
1
2C
2D1
B
Battery B±O
B 5 4F10
FL Block
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±785
979 Author: Date:
2005 SEQUOIA (RM1146U)
Height Control Indicator Lamp Circuit
CIRCUIT DESCRIPTION
The height control indicator lamp indicates the target height, not the actual height.
It blinks when the height control is operated by pressing the height control switch and stays on when the
operation is completed.
WIRING DIAGRAM
DIDEL±01
Page 991 of 4323
F19451
C6
Combination
MeterSuspension Control
ECU
I18
Ignition SW
Engine Room J/B Instrument Panel J/B B±O
W±R11
7 1H
1JIGN1
1C
1C32
B±RMAN. 24
13 LG11
S25 VN
5
IG2 AM2 6
W±R
B
Battery 1
2D AM2
2C1
B5 4F10
FL Block
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±789
983 Author: Date:
2005 SEQUOIA (RM1146U)
Height Control Manual Indicator Lamp Circuit
CIRCUIT DESCRIPTION
When manual mode is selected by pressing the height control mode select switch, the manual indicator lamp
comes on. (For the wiring diagram of the height control mode select switch circuit, see page DI±778.) If the
suspension control ECU detects a problem, the height control manual indicator lamp blinks while suspend-
ing the height control function. At the same time, the suspension control ECU records a DTC in the memory.
Connect terminals TC and CG of the DLC3 to make the height control manual indicator lamp blink and output
DTCs.
WIRING DIAGRAM
DIDEN±01