2001 TOYOTA SEQUOIA ECU

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±775
969 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:
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 ON, and turn the hand±held tester main switch ON.
(c) Select the item ºHEIGHT SW DOWNº or ºHEIGHT SW UPº in the DATA LIST, and read its value dis-
played on the hand±held tester.
AIR SUSPENSION:
ItemMeasurement Item / Range (Dis-
play)Normal ConditionDiagnostic Note
HEIGHT SW DOWNHeight control switch (DOWN) /
ON or OFFON: Height control switch
ºDOWNº button is pressed
OFF: ±
±
HEIGHT SW UPHeight control switch (UP) / ON or
OFFON: Height control switch ºUPº
button is pressed
OFF: ±
±
CHECK:
Check that the value displayed on the hand±held tester changes by pressing the height control switch ºUPº
or ºDOWNº.
OK:
Height control switch 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

F16805
Suspension Control ECU
Wire Harness View:
S25
UPSW
DNSW
F19462
Height Control Switch Wire Harness
Side Connector Front View:
H12
ELW S
HSW
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±777
971 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check harness and connector (Height control switch ± Suspension control ECU,
Body ground).
PREPARATION:
Disconnect the ECU connector.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Tester connection
(Symbol)ConditionSpecified condition
S25±13 (UPSW) ±
H12±3 (HSW)AlwaysBelow 1 W
S25±32 (DNSW) ±
H12±4 (LWS)AlwaysBelow 1 W
H12±2 (E) ± Body groundAlwaysBelow 1 W
S25±13 (UPSW) ±
Body groundAlways10 kW or higher
S25±32 (DNSW) ±
Body groundAlways10 kW or higher
NG Repair or replace harness or connector.
OK
Replace suspension control ECU
(See page IN±35).

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

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±779
973 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:
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 ON, and turn the hand±held tester main switch ON.
(c) Select the item ºHEIGHT SW HOLDº in the DATA LIST, and read its value displayed on the hand±held
tester.
AIR SUSPENSION:
ItemMeasurement Item / Range (Dis-
play)Normal ConditionDiagnostic Note
HEIGHT SW HOLDHeight control mode select switch
/ ON or OFFON: Height control mode select
switch is pressed
OFF: ±
±
CHECK:
Check that the value displayed on the hand±held tester changes by pressing the height control mode select
switch.
OK:
Height control mode select switch 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

F16805
Suspension Control ECU
Wire Harness View:
S25
TD
F19463
Height Control Mode Select Switch
Wire Harness Connector Front View:
H17
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±781
975 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check harness and connector (Height control mode select switch ± Suspension
control ECU).
PREPARATION:
Disconnect the ECU connector.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Tester connection
(Symbol)ConditionSpecified condition
S25±12 (TD) ± H17±3AlwaysBelow 1 W
H17±4 ± Body groundAlwaysBelow 1 W
S25±12 (TD) ±
Body groundAlways10 kW or higher
NG Repair or replace harness or connector.
OK
Replace suspension control ECU
(See page IN±35).

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

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±783
977 Author: Date:
2005 SEQUOIA (RM1146U)
DTC U0122/67 Lost Communication with Translate ECU
CIRCUIT DESCRIPTION
The translate ECU sends signals such as vehicle wheel speed signal, TS terminal signal (test mode signal)
to the suspension control ECU, etc. when the air suspension system is in operation.
DTC No.DTC Detecting ConditionTrouble Area
U0122/67
The suspension control ECU detects the following conditions
simultaneously:
1. Ignition switch ON
2. No communication from translate ECU continues for more
than 3 seconds

Translate ECU

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).
DIDEH±01

DI±784
± DIAGNOSTICSAIR SUSPENSION SYSTEM
978 Author: Date:
2005 SEQUOIA (RM1146U)
DTC U0132/71 Lost Communication with Ride Level Con-
trol Module
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
U0132/71
The suspension control ECU detects the following conditions
simultaneously:
1. Ignition switch ON
2. No communication from CAN bus continues for more than
10 times

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).
DIDEJ±01