TOYOTA SEQUOIA 2001 Service Repair Manual

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.

DI±760
± DIAGNOSTICSAIR SUSPENSION SYSTEM
954 Author: Date:
2005 SEQUOIA (RM1146U)
NG Replace height control valve assy
(See page SA±162).
NG Replace height control compressor assy
(See page SA±162).
OK
4 Inspect height control sensor sub±assy.
CHECK:
Inspect and adjust the height control sensor sub±assy (See page SA±156).
NEXT
5 Reconfirm DTC.
CHECK:
Clear the DTC and repeat the procedure to re±check it (See page DI±729).
HINT:
If the DTC C1751/51 is still output, proceed to the next step.
NEXT
Check and repair or replace malfunctioning
parts.
(a) Air tube is clogged (See page SA±156).
(b) Compressor is faulty (See page SA±162).
(c) Relief valve is faulty (See page SA±166).
(d) Height control sensor sub±assy is faulty (See page SA±156).
(e) Foreign material entered the height control solenoid valve (gate solenoid valve) and the exhaust sole-
noid valve.
(f) Air leakage due to damage to the height control cylinder assy (pneumatic cylinder).
(g) Suspension control ECU malfunctions (See page IN±35).

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±761
955 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1761/61 ECU Malfunction
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1761/61Suspension control ECU malfunction

Power source circuit

Suspension control ECU

Communication circuit
INSPECTION PROCEDURE
HINT:

If DTC C1774/74 (power source circuit) is displayed, perform the inspection necessary for DTC
C1774/74 first (See page DI±763).

If DTC U0122/67, U0100/65, U0132/71 and C1761/61 (ECU malfunction) are output at the same time,
perform the inspection necessary for the CAN communication system first.

The suspension control ECU, controlling the air suspension system, is activated when the ignition
switch is turned ON.
After 2 seconds, the ºMAIN RELAYº built in the ECU is activated and the system is driven by +B power
source.
Vehicle height may increase after turning the ignition switch off and unloading the vehicle/letting
people get out of the vehicle. In order to adjust the vehicle height, vehicle height control will continue
for a while from then.
DIDDY±01

F16805
S25
Wire Harness View:
BAT
B
GND
DI±762
± DIAGNOSTICSAIR SUSPENSION SYSTEM
956 Author: Date:
2005 SEQUOIA (RM1146U)
1 Inspect suspension control ECU (ECU power source).
PREPARATION:
Disconnect the ECU connector.
CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:
Tester connection
(Symbol)Conditionspecified condition
S25±24 (B) ±
S25±22 (GND)Always10 to 14 V
S25±25 (BAT) ±
S25±22 (GND)Always10 to 14 V
NG Check power source circuit
(See page DI±761).
OK
Replace suspension control ECU
(See page IN±35).

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

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).

F16805
S25
BAT
B
Wire Harness View:
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±765
959 Author: Date:
2005 SEQUOIA (RM1146U)
A
3 Inspect fuse (AIR SUS No. 2).
PREPARATION:
Remove the AIR SUS No. 2 fuse from the engine room R/B.
CHECK:
Check continuity of the AIR SUS No. 2 fuse.
OK:
Continuity
NG Inspect for short circuit in all harness and com-
ponents connected to AIR SUS No. 2 fuse.
OK
4 Inspect suspension control ECU.
PREPARATION:
Disconnect the ECU connector.
CHECK:
Measure the voltage between terminal S25±24 (B) of the sus-
pension control ECU connector and body ground and between
terminal S25±25 (BAT) and body ground.
OK:
Voltage: 10 to 14 V
NG Repair or replace harness or connector.
OK

F16805
Wire Harness View:
GND S25
DI±766
± DIAGNOSTICSAIR SUSPENSION SYSTEM
960 Author: Date:
2005 SEQUOIA (RM1146U)
5 Check harness and connector (Suspension control ECU ± Body ground).
CHECK:
Check continuity between terminal S25±22 (GND) and body
ground.
OK:
Continuity
NG Repair or replace harness or connector.
OK
Replace suspension control ECU
(See page IN±35).

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

F16805
Wire Harness View:
S25
STP
DI±768
± DIAGNOSTICSAIR SUSPENSION SYSTEM
962 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
1 Inspect stop light.
CHECK:
Check that the stop light comes on when the brake pedal is depressed and goes off when the brake pedal
is released.
OK:
Stop light operates normally.
NG Go to step 3.
OK
2 Inspect suspension control ECU.
PREPARATION:
Disconnect the ECU connector.
CHECK:
Measure the voltage between terminal S25±27 (STP) of the
suspension control ECU and body ground when the stop light
switch is ON and OFF.
OK:
Switch conditionSpecified condition
Brake pedal depressed (ON)10 to 14 V
Brake pedal released (OFF)Below 1 V
NG Repair or replace harness connector.
OK
Replace suspension control ECU
(See page IN±35).