2001 TOYOTA SEQUOIA engine

DIDDE±01
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±727
921 Author: Date:
2005 SEQUOIA (RM1146U)
DATA LIST / ACTIVE TEST
1. DATA LIST
HINT:
By accessing the DATA LIST displayed by the hand±held tester, you can read the value of the switches and
sensors and so on without removing any parts. Reading the DATA LIST is the first step of troubleshooting
and is one method to shorten labor time.
(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, read the DATA LIST.
AIR SUSPENSION:
ItemMeasurement Item / Range (Dis-
play)Normal ConditionDiagnostic Note
VEHICLE SPD
Vehicle speed reading / min.: 0
km/h (0 mph), max.: 255 km/h
(158 mph)
Actual vehicle speedSpeed indicated on the combina-
tion meter
FR WHEEL SPD
Wheel speed (Front right) reading /
min.: 0 km/h (0 mph), max.: 255
km/h (159 mph)
Actual vehicle speedSpeed indicated on the speedome-
ter
FL WHEEL SPD
Wheel speed (Front left) reading /
min.: 0 km/h (0 mph), max.: 255
km/h (159 mph)
Actual vehicle speedSpeed indicated on the speedome-
ter
IG VOLTAGEECU power supply voltage / min.:
0 V, max.: 25.5 VActual ECU power supply voltage:
10 to 14 V±
POWER VOLTAGE+B power source voltage / min.: 0
V, max.: 25.5 VActual battery power supply volt-
age: 10 to 14 V±
STEERING ANG
Steering angle sensor reading /
min.: ±49150.5 deg, max.: 49152
degActual steering angle /
Left turn: reading increases
Right turn: reading increasesZero point is set at the point when
battery is connected
ENGINE SPDCrankshaft position sensor read-
ing / min.: 0 rpm, max.: 25,500 rpmActual engine speedSpeed indicated on the combina-
tion meter
HEIGHT SW DOWNHeight control switch (DOWN) /
ON or OFFON: Height control switch
ºDOWNº button pressed
OFF: ±
±
HEIGHT SW UPHeight control switch (UP) / ON or
OFFON: Height control switch ºUPº
button pressed
OFF: ±
±
HEIGHT SW HOLDHeight control mode select switch
/ ON or OFFON: Height control mode select
switch pressed
OFF: ±
±
STOP LIGHT SWStop light switch / ON or OFFON: Brake pedal depressed
OFF: Brake pedal released±
DOOR SWDoor courtesy light switch / ON or
OFFON: Open each door
OFF: Close all doors±
L4 SW4LO switch / ON or OFFON: 2WD/4HI switch pressed
OFF: ±±
TSTS terminal / ON or OFFON: During test mode
OFF: Normal mode±
TCTC terminal / ON or OFFON: DTC recorded
OFF: No DTC recorded±
SOL SLRLHeight control valve solenoid (Lev-
elling solenoid valve) / ON or OFFON: Leveling solenoid operated
OFF: Leveling solenoid not oper-
ated
±
SOL SLRGHeight control valve solenoid
(Gate solenoid valve) / ON or OFFON: Gate solenoid operated
OFF: Gate solenoid not operated±

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.

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

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

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).

F19444
Height Control Compressor
(Compressor/Height Control Dryer)
H133
Engine Room R/B No. 2
W±B
Battery J28
J/CR±L
BM23
IN115
S2520
2
3
25
1W
9B
5
J8
J/C
AAW±B
1K12
1F9
A W±B
IESuspension
Control
ECU
RC F10
Fusible Link Block
AIR SUS
Instrument
Panel J/BRM+ R±L R±L
H134
BR±Y
BM24
IA121S2521
BR±Y BR±Y
RM±
AIR SUS Relay H131
W
BM21
IC48
WW W
22
2 S255
G±Y IN16
IA125
G±Y
BJ H132
BM22
W±B
AJ19
J/C W±BALT
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±753
947 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM

F19461
Height Control Compressor
Connector Front View:
H13
DI±756
± DIAGNOSTICSAIR SUSPENSION SYSTEM
950 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check harness and connector (Height control compressor ± Battery, Body
ground).
PREPARATION:
(a) Reconnect the ECU connector.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:
Tester connectionConditionSpecified value
H13±1 ± Body ground
Engine idling, height con-
trol switch is pushed from
ºNº to ºUPº
10 to 14 V
HINT:
Measure the voltage within 90 seconds.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Tester connectionConditionSpecified value
H13±2 ± Body groundAlwaysBelow 1 W
NG Repair or replace harness or connector.
OK
Replace suspension control ECU
(See page IN±35).

± 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