2001 TOYOTA SEQUOIA O2 sensor

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±757
951 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1751/51 Continuous Electric Current To Height Con-
trol Compressor
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1751/51*1With the AIR SUS relay activated, the vehicle does not go up
to the standard vehicle height after the 90 sec. have elapsed.

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
*1: The compressor motor operates continuously to raise vehicle height and allows electric current flow to
the AIR SUS relay for 90 seconds or more under the following conditions:

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.

If the compressor remains on because the vehicle is jacked up, the vehicle height is set at a position
lower than normal while the engine is running and then the vehicle height control function raises the
vehicle.
Thus DTC C1751/51 may be output and vehicle height control may be suspended. (This is not electrically
abnormal.) In this case, however, the vehicle height operation is resumed approx. 10 min. after the ignition
switch is turned ON after the ECU detects the first error. If ECU detects another error, it takes 70 minutes
until control is resumed.
WIRING DIAGRAM
See page DI±752.
DIDDV±01

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).

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

F19447
Body ECUSuspension Control
ECU
ACTY20
B631
S25 DOOR R DI±770
± DIAGNOSTICSAIR SUSPENSION SYSTEM
964 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1783/83 Door Courtesy Switch Circuit
(Test Diagnosis)
CIRCUIT DESCRIPTION
The door courtesy light switch turns on when the door is opened and turns off when the door is closed.
The signal is sent from the body ECU and the back door ECU into the DOOR terminal of the suspension
control ECU when any door is open.
HINT:
This DTC is output only when the sensor signal check is done.
For courtesy light switch connection, see the system diagram on page DI±698.
DTC No.DTC Detecting ConditionTrouble Area
C1783/83Door courtesy light switch signal does not change.

Door courtesy light switch

Back door lock assy (Back door courtesy light switch)

Door courtesy light switch circuit

Body ECU

Back door ECU

Suspension control ECU
WIRING DIAGRAM
DIDEA±01

F19448
H12
Height Control SwitchSuspension Control
ECU
IMS25 313
S25 HI
LOHSW
LW S
DNSW 32
4 2 W±BUPSW
W L±B
E DI±774
± DIAGNOSTICSAIR SUSPENSION SYSTEM
968 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1786/86 Height Control Switch Circuit
(Test Diagnosis)
CIRCUIT DESCRIPTION
Vehicle height can be chosen by pressing the height control switch.
By pressing the ºUPº side, vehicle height goes up.
By pressing the ºDOWNº side, vehicle height goes down.
HINT:
This DTC is output only when the sensor signal check is done.
DTC No.DTC Detecting ConditionTrouble Area
C1786/86Height control switch signal does not change.

Height control switch

Height control switch circuit

Suspension control ECU
WIRING DIAGRAM
DIDED±01

F19449
H17
Height Control Mode
Select SwitchSuspension Control
ECU
W±B
IM4BR±B
312
S25
TD DI±778
± DIAGNOSTICSAIR SUSPENSION SYSTEM
972 Author: Date:
2005 SEQUOIA (RM1146U)
DTC C1788/88 Height Control Mode Select Switch Circuit
(Test Diagnosis)
CIRCUIT DESCRIPTION
Height control can be operated or suspended by pressing the height control mode select switch.
By pressing the switch once, height control can be suspended.
By pressing the switch one more time, height control can be operated.
HINT:
The DTC is output only when the sensor signal check is done.
DTC No.DTC Detecting ConditionTrouble Area
C1788/88Height control mode select switch signal does not change.

Height control mode select switch

Height control mode select switch circuit

Suspension control ECU
WIRING DIAGRAM
DIDEF±01

DIDJU±01
F19149
Tire Pressure Sensor
(Tire Pressure Monitor
Valve Sub±assy)
Tire Pressure Sensor
(Tire Pressure Monitor
Valve Sub±assy)Tire Pressure Sensor
(Tire Pressure Monitor
Valve Sub±assy) Combination Meter Assy

Tire Pressure Warning Lamp
Tire Pressure
Monitor ECU
Tire Pressure Warning
Reset Switch
Tire Pressure Sensor
(Tire Pressure Monitor Valve Sub±assy) Tire Pressure Sensor
(Tire Pressure Monitor
Valve Sub±assy)
Tire Pressure Monitor
Receiver Assy
DI±798
± DIAGNOSTICSTIRE PRESSURE WARNING SYSTEM
992 Author: Date:
2005 SEQUOIA (RM1146U)
LOCATION

DIDJV±01
F19126
Combination meter assy
(Vehicle speed signal)
Tire pressure monitor receiver assyCombination meter assy
(Tire pressure warning lamp) Tire
Pressure
Monitor
ECU
: Radio signal
Tire Pressure Sensor
(Tire pressure monitor valve
sub±assy) (FR LH)
Tire Pressure Sensor
(Tire pressure monitor valve
sub±assy) (FR RH)
Tire Pressure Sensor
(Tire pressure monitor valve
sub±assy) (RR LH)
Tire Pressure Sensor
(Tire pressure monitor valve
sub±assy) (RR RH)
Tire Pressure Sensor
(Tire pressure monitor valve
sub±assy) (SPARE)
DLC3
Tire pressure warning reset switch
± DIAGNOSTICSTIRE PRESSURE WARNING SYSTEM
DI±799
993 Author: Date:
2005 SEQUOIA (RM1146U)
SYSTEM DIAGRAM