2001 TOYOTA SEQUOIA engine

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

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

DI±782
± DIAGNOSTICSAIR SUSPENSION SYSTEM
976 Author: Date:
2005 SEQUOIA (RM1146U)
DTC U0100/65 Lost Communication with ECM/PCM
CIRCUIT DESCRIPTION
The ECM sends signals such as engine speed signal, transmission signal, shift position signal, L4 switch
signal, TC terminal signal (diagnosis mode signal) to the suspension control ECU, etc. when the air suspen-
sion system is in operation.
DTC No.DTC Detecting ConditionTrouble Area
U0100/65
The suspension control ECU detects the following conditions
simultaneously:
1. Ignition switch ON
2. Vehicle speed signal is more than 30 km/h (18.5 mph)
3. No communication from ECM continues for more than 3
seconds

ECM

Suspension control ECU

Communication circuit
INSPECTION PROCEDURE
HINT:
This circuit uses CAN for communication. Therefore, if there are any malfunctions in the communication cir-
cuit, one or more DTCs in the CAN communication system is/are output.
1 Go to CAN communication system (See page DI±1065).
DIDEG±01

F19450
C6
Combination
MeterSuspension Control
ECU
I18
Ignition SW Instrument Panel J/B
Engine Room J/B24
14
15
16 LO
N
HIP
B±L
GR±R26
S25
9
S25
8
S25LO
NR
HI
6
IG2 AM25
W±R B±R IGN1 11
7 1H
1J1C
1C32
W±R
AM2
1
2C
2D1
B
Battery B±O
B 5 4F10
FL Block
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±785
979 Author: Date:
2005 SEQUOIA (RM1146U)
Height Control Indicator Lamp Circuit
CIRCUIT DESCRIPTION
The height control indicator lamp indicates the target height, not the actual height.
It blinks when the height control is operated by pressing the height control switch and stays on when the
operation is completed.
WIRING DIAGRAM
DIDEL±01

F19451
C6
Combination
MeterSuspension Control
ECU
I18
Ignition SW
Engine Room J/B Instrument Panel J/B B±O
W±R11
7 1H
1JIGN1
1C
1C32
B±RMAN. 24
13 LG11
S25 VN
5
IG2 AM2 6
W±R
B
Battery 1
2D AM2
2C1
B5 4F10
FL Block
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±789
983 Author: Date:
2005 SEQUOIA (RM1146U)
Height Control Manual Indicator Lamp Circuit
CIRCUIT DESCRIPTION
When manual mode is selected by pressing the height control mode select switch, the manual indicator lamp
comes on. (For the wiring diagram of the height control mode select switch circuit, see page DI±778.) If the
suspension control ECU detects a problem, the height control manual indicator lamp blinks while suspend-
ing the height control function. At the same time, the suspension control ECU records a DTC in the memory.
Connect terminals TC and CG of the DLC3 to make the height control manual indicator lamp blink and output
DTCs.
WIRING DIAGRAM
DIDEN±01

F19174
Combination MeterTire Pressure
Monitor ECU
Engine Room J/B I18
Ignition SW IGN1
B±O
IG2 AM2 1C11
Battery 2
1H
T17 C5GR±L
Tire Pressure
B±R
B 56
54AM2 24
6IND Instrument Panel J/B
C620
2D1
2C1 1C3
1J7
F10
Fusible Link BlockInstrument Panel J/B
W±R
W±R
B
± DIAGNOSTICSTIRE PRESSURE WARNING SYSTEM
DI±873
1067 Author: Date:
2005 SEQUOIA (RM1146U)
Tire Pressure Warning Lamp Circuit
CIRCUIT DESCRIPTION
If the ECU detects trouble, the tire pressure warning lamp comes on and tire pressure monitor is cancelled
at the same time. At this time, the ECU records a DTC in memory.
Connect terminals Tc and CG of the DLC3 to make the tire pressure warning lamp blink and output the DTC.
WIRING DIAGRAM
DIDKF±01

F19790
Combination MeterTire Pressure
Monitor ECU
Engine Room J/B I18
Ignition SWIGN1
B±O
IG2AM2 1C11
Battery 2
1HT17
C5GR±L
Tire Pressure
B±R
B 56
54AM2 24
6IND Instrument Panel J/B
C620
2D1
2C1 1C3
1J7
F10
Fusible Link BlockInstrument Panel J/B
W±R
W±R
B
T17 T18 Tire Pressure
Warning Reset SW
G±R
CALSW
GND
T17 1H
1H
1F7
1 10
W±B11 10 Instrument Panel J/B
W±B
A J8
J/C
IE1 2
± DIAGNOSTICSTIRE PRESSURE WARNING SYSTEM
DI±875
1069 Author: Date:
2005 SEQUOIA (RM1146U)
Tire Pressure Warning Reset Switch Circuit
CIRCUIT DESCRIPTION
Receiving the signal from the tire pressure warning reset switch, the tire pressure monitor ECU indicates the
initialization of the pressure warning system.
WIRING DIAGRAM
DIDKG±01

DIDLX±01
DI±894
± DIAGNOSTICSABS WITH EBD & BA & TRAC & VSC SYSTEM
1088 Author: Date:
2005 SEQUOIA (RM1146U)
SYSTEM DESCRIPTION
1. SYSTEM DESCRIPTION
HINT:

The yaw rate sensor and deceleration sensor are combined and in a single unit. This unit communi-
cates with the skid control ECU through the CAN communication system.

No changes have been made to the communication method between the VSC system and ECM. How-
ever, the communication method between the Translate ECU and ECM has been changed from serial
to CAN communication.
(a) ABS
(Anti±lock Brake System)
The ABS helps prevent the wheels from locking when the brakes are applied firmly or when braking
on a slippery surface.
(b) EBD
(Electronic Brake force Distribution)
The EBD control utilizes ABS, realizing proper brake force distribution between front and rear wheels
in accordance with driving conditions.
In addition, during braking while cornering, it also controls the brake forces of the right and left wheels,
helping to maintain vehicle behavior.
(c) BA (Brake Assist)
The primary purpose of the brake assist system is to provide an auxiliary brake force to assist the driver
who cannot generate a large enough brake force during emergency braking, thus helping to maximize
the vehicle's braking performance.
(d) TRAC
(Traction Control)
The TRAC system helps prevent the drive wheels from slipping if the driver presses down on the accel-
erator pedal excessively when starting off or accelerating on a slippery surface.
(e) VSC
(Vehicle Stability Control)
The VSC system helps prevent the vehicle from slipping sideways as a result of strong front wheel skid
or strong rear wheel skid during cornering.
2. ABS with EBD & BA & TRAC & VSC OPERATION
(a) The skid control ECU calculates vehicle stability tendency based on signals from the speed sensor,
yaw rate (deceleration) sensor and steering angle sensor. In addition, it evaluates the results of the
calculations to determine whether any control actions (control of the engine output torque by electronic
throttle control and of the wheel brake pressure by the brake actuator) should be implemented.
(b) The SLIP indicator blinks and the VSC buzzer sounds to inform the driver that the VSC system is oper-
ating. The SLIP indicator also blinks when TRAC is operating, and the operation being performed is
displayed.
3. FAIL SAFE FUNCTION
(a) When a failure occurs in the ABS & BA & TRAC & VSC systems, the ABS and VSC warning lights come
on and ABS & BA & TRAC & VSC operations are prohibited. In addition to this, when there is a failure
that disables EBD operation, the brake warning light also comes on and EBD operation is prohibited.
(b) If some control is prohibited due to a malfunction during its operation, that control will be cut off gradual-
ly not to change the stability of the vehicle suddenly.