TOYOTA SEQUOIA 2001 Service Repair Manual

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

DI±730
± DIAGNOSTICSAIR SUSPENSION SYSTEM
924 Author: Date:
2005 SEQUOIA (RM1146U)
HINT:
*
1: For codes marked with a ºº in the ºManual Indicator Lampº column, the height control manual indicator
lamp blinks at 1 second intervals.
*
2: The codes marked with a ºº in the ºMemoryº column are stored in the memory even when the ignition
switch is OFF, but the codes marked with ºXº are not.
*
3: The relief pressure of the compressed air is 980 kPa (10 kgf/cm2, 142 psi). DTC C1751/51 may be output
and vehicle height control may be suspended under the following conditions (not abnormal):

Vehicle height control is attempted on a steep slope when the vehicle is overloaded.

The compressor remains on for an excessive period of time or repeatedly turns on and off because
of continuous height control switch operation.

The vehicle height control function (UP) operates when the vehicle height is set at a position lower than
normal while the engine is running.

DIDDK±01
F19441
SHB H15
Height Control Sensor Sub±assy
1 G±OSuspension Control ECU
SBL
BM1G±O 5
IN118
G±O
S2515
SHRL2
GR±L
BM16
IN117
S2517
GR±LGR±L
SHRL
SHG3
L±R
BM17
L±RL±R
IN116
S2519
SGL
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±731
925 Author: Date:
2005 SEQUOIA (RM1146U)
CIRCUIT INSPECTION
DTC C1714/14 Left Rear Height Control Sensor Circuit
CIRCUIT DESCRIPTION
A magnetic circuit installed on the shaft inside the height control sensor rotates around the linear IC. The
linear IC outputs voltage corresponding to the level of magnetic strength generated by the magnetic circuit.
As a result, voltage corresponding to the shaft rotation angle is supplied to the suspension control ECU.
DTC No.DTC Detecting ConditionTrouble Area
C1714/14
Either of the following conditions is detected:
1. With the ignition switch ON, a voltage of the height control
sensor sub±assy is 4.7 V or more or 0.3 V or less for 1 sec.
or more.
2. With the ignition switch ON, a voltage of the height control
sensor sub±assy is 5.5 V or more or 4.3 V or less for 0.5
sec. or more.

Height control sensor sub±assy

Height control sensor circuit

Suspension control ECU
HINT:

Once the ECU stores DTC C1714/14 in the memory, vehicle height control is suspended until a normal
signal is input to the ECU from the height control sensor sub±assy. However, control resumes if the
ignition switch is turned OFF, and then turned ON again.

When the suspension control ECU detects a malfunction in the height control sensor, the height control
indicator lamp ºNº comes on or blinks, and control of the height control sensor ºUPº and ºDOWNº opera-
tion is halted.
WIRING DIAGRAM

DI±732
± DIAGNOSTICSAIR SUSPENSION SYSTEM
926 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:

Proceed to troubleshooting following the flow chart, regardless of whether or not DTC C1714/14 is dis-
played.

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 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 Read value of the hand±held tester.
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to the ON position, and push the hand±held tester main switch ON.
(c) Select the item ºRL HEIGHTº in the DATA LIST, and read its value displayed on the hand±held tester.
AIR SUSPENSION:
ItemMeasurement Item / Range (Dis-
play)Normal ConditionDiagnostic Note
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.)
±
CHECK:
Check the vehicle height value of the height control sensor sub±assy with the hand±held tester while press-
ing the height control switch ºUPº or ºDOWNº.
OK:
Vehicle height value changes.
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

F19456
Wire Harness Connector
Front View:
H15
SHB
SHG
F16805
S25
Suspension Control ECU
Wire Harness View:
SGL
SBL
F19456
Height Control Sensor Sub±assy
Connector Front View:
SHG H15
SHB
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±733
927 Author: Date:
2005 SEQUOIA (RM1146U)
2 Check harness and connector (Height control sensor sub±assy power source).
PREPARATION:
(a) Disconnect the height control sensor sub±assy connec-
tor.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals 1 (SHB) and 3 (SHG)
of the height control sensor sub±assy wire harness side con-
nector.
OK:
Voltage: 4.5 to 5.5 V
OK Go to step 4.
NG
3 Check harness and connector (Height control sensor sub±assy ± Suspension
control ECU).
PREPARATION:
Disconnect the ECU connector.
CHECK:
(a) Check for an open or short circuit in the harness and the
connector between terminal 1 (SHB) of the height control
sensor sub±assy and S25±15 (SBL) of the suspension
control ECU.
(b) Check for an open or short circuit in the harness and the
connector between terminal 3 (SHG) of the height control
sensor sub±assy and S25±19 (SGL) of the suspension
control ECU.
OK:
There is no open or short circuit in the wire harness.

F16805
S25
Suspension Control ECU
Wire Harness View:
SHRL
F19456
Height Control Sensor Sub±assy
Connector Front View:
H15
SHRL
DI±734
± DIAGNOSTICSAIR SUSPENSION SYSTEM
928 Author: Date:
2005 SEQUOIA (RM1146U)
NG Repair or replace harness or connector.
OK
4 Check harness and connector (Height control sensor sub±assy ± Suspension
control ECU.
CHECK:
Check for an open or short circuit in the harness and the con-
nector between terminal 2 (SHRL) of the height control sensor
sub±assy and S25±17 (SHRL) of the suspension control ECU.
OK:
There is no open or short in the wire harness.
NG Repair or replace harness or connector.
OK

F16806
High (45°)Low (±45°)
Normal (0°)
Connector Front View:
SHG SHRLSHB
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±735
929 Author: Date:
2005 SEQUOIA (RM1146U)
5 Inspect height control sensor sub±assy.
PREPARATION:
(a) Remove the height control sensor sub±assy.
(b) Connect 3 dry batteries of 1.5 V in series.
CHECK:
Connect terminal 1 (SHB) to the batteries' positive (+) terminal,
and terminal 3 (SHG) to the batteries' negative (±) terminal,
then apply approximately 4.5 V between terminals 2 (SHRL)
and 3 (SHG) in the following conditions.
OK:
PositionVoltage
High (0 to 45)Approx. 2.25 to 4.05 V
Normal (0)Approx. 2.25 V
Low (0 to ±45)Approx. 0.45 to 2.25 V
NG Replace height control sensor sub±assy.
OK
Replace suspension control ECU
(See page IN±35).

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

F19437
Connector Front View:
32 1
DI±738
± DIAGNOSTICSAIR SUSPENSION SYSTEM
932 Author: Date:
2005 SEQUOIA (RM1146U)
2 Inspect gate solenoid valve (height control valve).
PREPARATION:
Disconnect the valve connector.
CHECK:
Measure the resistance between terminals.
OK:
Solenoid valveTester connectionResistance
Gate solenoid valve1 ± 217.5 to 21.5 W
CHECK:
Check the operating sound of the valves when battery voltage
is applied to the terminals as shown below.
Solenoid valveBattery positiveBattery negative
Gate solenoid valve12
OK:
Operating sound (clicking) can be heard.
HINT:
When a malfunction is found in the gate solenoid valve, replace
the height control valve.
NG Replace height control valve
(See page SA±166).
OK