Page 930 of 4323
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
Page 931 of 4323
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 circuitHeight control sensor sub±assy
Height control sensor circuit
Suspension control ECU
C1733/33
(DI±736)Open or short in gate solenoid
valve circuitGate 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 circuitLeveling 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 circuitExhaust 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
circuitAIR SUS relay
AIR SUS relay circuit
Suspension control ECU
C1742/42
(DI±752)Lock, open or short in height
control compressor circuitHeight 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/
PCMECM
Suspension control ECU
Communication circuit
XX
U0122/67
(DI±783)Lost communication with TL
ECUTranslate ECU
Suspension control ECU
Communication circuit
XX
U0132/71
(DI±784)Lost communication with ride
level control moduleSuspension control ECU
Communication circuitXX
Page 949 of 4323
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±747
941 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1741/41 Air Sus Relay Circuit
CIRCUIT DESCRIPTION
When the ºUPº side of the height control switch is pressed, a signal is sent from terminal RC of the suspen-
sion control ECU to the AIR SUS relay to turn it on.
As a result, the current flows to the AIR SUS relay coil, closing the relay contact, and then the battery positive
voltage is applied to the compressor, which causes the compressed air to raise the vehicle height.
DTC No.DTC Detecting ConditionTrouble Area
C1741/41
Either of the following conditions is detected:
1. With the AIR SUS relay inactivated, an open signal of the
AIR SUS relay is detected for 1 sec. or more.
2. With the AIR SUS relay activated, a short signal of the AIR
SUS relay is detected 8 times successively.
AIR SUS relay
AIR SUS relay circuit
Suspension control ECU
HINT:
Once the ECU stores DTC C1741/41 in the memory, the vehicle height control is suspended until a normal
signal is input to the ECU from the AIR SUS relay. However, the control resumes if the ignition switch is turned
OFF, and then turned ON again.
DIDDT±01
Page 950 of 4323
F19443
Height Control
Compressor
H131
Engine Room R/B No. 2
G±Y AIR SUS Relay
Battery J28
J/C W
BM21
IC48
IA121
WWW
2
22
2 3
25
1W
9B
5
W±B
J8
J/C
AAW±B
1K12
1F9
A W±B
IESuspension
Control
ECU
IA125
G±Y
S255
RC F10
Fusible Link Block
ALT
Instrument
Panel J/BAIR SUS DI±748
± DIAGNOSTICSAIR SUSPENSION SYSTEM
942 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
Page 951 of 4323
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±749
943 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 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 by 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 ºMOTOR RELAYº in the ACTIVE TEST, and operate it with the hand±held tester.
AIR SUSPENSION:
ItemVehicle Condition / Test DetailsDiagnostic Note
MOTOR RELAYTurn AIR SUS relay / ON or OFFOperation sound of motor can be heard
CHECK:
Check the operating sound of the AIR SUS relay when operating it with the hand±held tester.
OK:
The operating sound of the AIR SUS relay can be heard.
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
Page 952 of 4323
F19458
DI±750
± DIAGNOSTICSAIR SUSPENSION SYSTEM
944 Author: Date:
2005 SEQUOIA (RM1146U)
2 Inspect AIR SUS relay.
PREPARATION:
Remove the AIR SUS relay from the engine room R/B No. 2.
CHECK:
Check continuity between each terminal of the AIR SUS relay.
OK:
Tester connectionResistance
3 ± 510 kW or higher
3 ± 5
Below 1 W
(When battery voltage is applied to ter-
minals 1±2)
NG Replace AIR SUS relay.
OK
Page 953 of 4323
F16805
S25
Suspension Control ECU
Wire Harness View:
RC
F19460
Engine Room R/B No. 2:
AIR SUS
Relay Terminal
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±751
945 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check harness and connector (Engine room R/B ± Suspension control ECU,
Body ground).
PREPARATION:
Disconnect the ECU connector.
CHECK:
Check for an open or short circuit in the harness and the con-
nector between the AIR SUS relay terminal 1 of the engine
room R/B and terminal S25±5 (RC) of the suspension control
ECU.
OK:
There is no open or short in the wire harness.
CHECK:
Check for an open circuit in the harness and the connector be-
tween the AIR SUS relay terminal 2 of the engine room R/B and
body ground.
OK:
There is no open in the wire harness.
NG Repair or replace harness or connector.
OK
Replace suspension control ECU
(See page IN±35).
Page 954 of 4323
DI±752
± DIAGNOSTICSAIR SUSPENSION SYSTEM
946 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1742/42 Height Control Compressor Circuit
CIRCUIT DESCRIPTION
When the ºUPº side of the height control is pressed, a signal is sent from terminal RC of the suspension con-
trol ECU to switch the AIR SUS relay ON. As a result, the relay contacts close and the compressor motor
turns on, producing compressed air.
The suspension control ECU detects the amount of current flow to the compressor motor by means of the
differences in potential at terminals RM+ and RM± of the suspension control ECU. In this way, the suspen-
sion control ECU monitors the compressor circuit for abnormalities.
DTC No.DTC Detecting ConditionTrouble Area
C1742/42
With the AIR SUS relay activated, a lock, open or short signal
of the height control compressor motor is detected for 4 sec. or
more.Height control compressor assy
Height control compressor circuit
Suspension control ECU
HINT:
Once the ECU stores DTC C1742/42 in the memory, the vehicle height control is not carried out until the
normal signal is input to the ECU from the compressor motor. However, the control automatically resumes
approx. 70 min. after the ignition switch is turned ON.
DIDDU±01
