2001 TOYOTA SEQUOIA Page 18

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±715
909 Author: Date:
2005 SEQUOIA (RM1146U)
Test mode (input signal check) table:
Check ItemOperation (A)Operation (B)
Stop light switch signalOFF (Brake pedal not depressed)ON (Brake pedal depressed)
Door courtesy light switch signalON (Each door opened)OFF (All doors closed)
Height control switch signal±Press the height control switch ºUPº first and
then press ºDOWNº
Height control mode select switch signalOFF (Height control mode select switch not
pushed in)ON to OFF (Height control mode select switch
pushed in and released)
HINT:
In step (6), all signals can be checked together.
(7) Read the test mode DTCs by following the prompts
on the tester screen.
HINT:
Refer to the hand±held tester operator's manual for further de-
tails.
(8) Check the malfunction using the code table below.
DTC of air suspension system test mode (input signal check) function:
If a trouble code is displayed during the test mode DTC check, check the circuit listed for that code. For details
of each code, refer to ºSee pageº under the respective DTC No. in the chart.
DTC No.
(See Page)Detection ItemTrouble Area
C1782/82
(DI±767)Stop light switch circuit malfunction

Stop light switch assy

Stop light switch circuit

Suspension control ECU
C1783/83
(DI±770)Door courtesy switch circuit malfunction

Door courtesy light switch assy

W/ Motor back door assy

Door courtesy light switch circuit

Body ECU

Back door ECU

Suspension control ECU
C1786/86
(DI±774)Height control switch circuit malfunction

Height control switch

Height control switch circuit

Suspension control ECU
C1788/88
(DI±778)Height control mode select switch circuit malfunction

Height control mode select switch

Height control mode select switch circuit

Suspension control ECU
(9) After completing the test mode, disconnect the tes-
ter and turn the ignition switch off.

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

DIDD7±01
C00083DLC3
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±721
915 Author: Date:
2005 SEQUOIA (RM1146U)
DIAGNOSIS SYSTEM
1. DIAGNOSIS SYSTEM
(a) Inspect the battery voltage.
Battery voltage: 11 to 14 V
If voltage is below 11 V, recharge the battery before proceeding.
(b) Check DLC3.
The suspension control ECU uses the CAN system and
ISO 9141±2 for communication. The terminal arrange-
ment of the DLC3 complies with SAE J1962 and matches
the ISO 9141±2 format.
Verify the conditions listed in the table below:
Symbols (Terminal No.)Terminal DescriptionConditionSpecified Condition
SIL(7) ± SG(5)Bus º+º lineDuring communicationPulse generation
CG(4) ± Body groundChassis groundAlwaysBelow 1 W
SG(5) ± Body groundSignal groundAlwaysBelow 1 W
BAT(16) ± Body groundBattery positiveAlways11 to 14 V
CANH(6) ± CANL (14)HIGH±level CAN bus lineIG switch OFF54 to 67 W
CANH(6) ± Battery positiveHIGH±level CAN bus lineIG switch OFF1 MW or higher
CANH(6) ± CG(4)HIGH±level CAN bus lineIG switch OFF3 KW or higher
CANL(14) ± Battery positiveLOW±level CAN bus lineIG switch OFF1 MW or higher
CANL(14) ± CG(4)LOW±level CAN bus lineIG switch OFF3 KW or higher
HINT:
If the hand±held tester display shows UNABLE TO CONNECT
TO VEHICLE when the cable of the hand±held tester is con-
nected to the DLC3, the ignition switch is turned ON and the tes-
ter is operated, there is a problem on the vehicle side or tester
side.

If communication is normal when the tester is connected
to another vehicle, inspect the DLC3 on the original ve-
hicle.

If communication is still not possible when the tool is con-
nected to another vehicle, the problem is probably in the
tester itself, so consult the service department listed in the
tester 's instruction manual.
(c) DTCs (Normal mode)
(1) DTCs are memorized in the suspension control
ECU and read by using the SST check wire or the
hand±held tester (see page DI±723 for the proce-
dure of DTCs check).
SST 09843±18040
(d) Test mode (Input signal check)
(1) By switching from normal mode into test mode, you
can inspect the height control switch, height control
mode select switch, door courtesy lamp switch, and
stop lamp switch (see page DI±711).

F16799
DI±722
± DIAGNOSTICSAIR SUSPENSION SYSTEM
916 Author: Date:
2005 SEQUOIA (RM1146U)
(e) Check the indicator lamp.
(1) Turn the ignition switch to the ON position.
(2) Check that the height control manual indicator lamp
and the height control indicator lamp come on for 2
seconds.
If the indicator check result is not normal, proceed to trouble-
shooting for the height control indicator lamp circuit (See page
DI±785) and the height control manual indicator lamp circuit
(See page DI±789).

DIDDA±01
C00083
DLC3
CG TC
F16800
Height
Control
Manual
Indicator
Lamp
F16801
ON0.25 sec.
OFF
0.25 sec.
0.5 sec.
1.5 sec.4.5 sec. 2.5 sec.
0.5 sec. ON
OFF Normal:
Codes 13 and 33:
1.5 sec.
Repeat
C00083
DLC3
CG TC
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±723
917 Author: Date:
2005 SEQUOIA (RM1146U)
DTC CHECK / CLEAR
1. DTC CHECK (USING SST CHECK WIRE)
(a) Checking DTCs using the SST check wire.
SST 09843±18040
(1) Using the SST, connect terminals TC and CG of the
DLC3.
(2) Turn the ignition switch to the ON position.
(3) Read and record any DTCs from the height control
manual indicator lamp on the combination meter.
As examples, the blinking patterns of a normal sys-
tem code and codes 13 and 33 are shown on the
left.
HINT:

If the height control manual indicator lamp does not show
any DTC or a normal system code, inspect the height con-
trol manual indicator lamp circuit
(See page DI±789).

The TC terminal circuit uses CAN for communication.
Therefore, if there are any malfunctions in the commu-
nication circuit, one or more DTCs in the CAN commu-
nication system is/are output.

If 2 or more malfunctions are indicated at the same time,
the lowest numbered DTC is displayed first.
(4) Refer to the Diagnostic Trouble Code Chart (See
page DI±729) for DTC information.
(5) After completing the check, remove the SST check
wire from the DLC3.
SST 09843±18040
(b) Clearing the DTCs using the SST check wire.
SST 09843±18040
(1) Using SST, connect terminals TC and CG of the
DLC3.
(2) Turn the ignition switch to the ON position.

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±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

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).