2001 TOYOTA SEQUOIA ECU

DIDCP±01
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±707
901 Author: Date:
2005 SEQUOIA (RM1146U)
HOW TO PROCEED WITH TROUBLESHOOTING
1 Vehicle Brought to Workshop
NEXT
2 Customer Problem Analysis (See page DI±710)
NEXT
3 Check CAN Communication System (See page DI±1065)
Check if any DTCs are output.
HINT:
The suspension control ECU of this system is connected to the CAN communication system. Therefore, be-
fore starting troubleshooting, make sure to check that there is no trouble in the CAN communication system.
CAN System DTC is Output (Proceed To ºCAN
COMMUNICATION SYSTEMº (See page
DI±1065))
No CAN System DTC is Output (Go to step 4)
4 Check and Clear DTCs (See page DI±723)
NEXT
5 Problem Symptom Confirmation
Symptom Does Not Occur (Go to step 6)
Symptom Occurs (Go to step 7)

DIDCV±01
C00083
DLC3
CG TS
F16800
Height
Control
Manual
Indicator
Lamp
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±711
905 Author: Date:
2005 SEQUOIA (RM1146U)
TEST MODE PROCEDURE
1. INPUT SIGNAL CHECK (Using SST check wire)
HINT:

This function checks if signals from the stop light switch
assy and the door courtesy lamp switch, etc. are being in-
put normally to the ECU.

When entering test mode, the suspension control ECU
sets all the test mode DTCs first.
After completing the test mode for each check item, the
test mode DTCs that are determined normal by the sus-
pension control ECU will be erased.
The test mode DTCs for other check items may not be
erased when only a certain signal is inspected.

When the test mode returns back to normal mode, all the
test mode DTCs will be erased.
(a) Procedure for Input Signal Check Mode (Test Mode) us-
ing SST check wire.
SST 09843±18040
(1) Make sure the ignition switch is OFF.
(2) Set each of the check items to the condition shown
under Operation (A) in the test mode table on the
next page.
(3) Using SST, connect terminals TS and CG of the
DLC3.
(4) Turn the ignition switch to the ON position.
(5) Check that the height control manual indicator lamp
is blinking.
HINT:

The height control manual indicator lamp comes on for 2
seconds, then blinks at 0.25 sec. intervals.

If the height control manual indicator light does not blink,
inspect the height control manual indicator lamp circuit
(See page DI±789).

A08841
Hand±held
Tester
DLC3
DI±714
± DIAGNOSTICSAIR SUSPENSION SYSTEM
908 Author: Date:
2005 SEQUOIA (RM1146U)
DTC of air suspension system test mode (input signal check) function:
If a trouble code is displayed during the test mode DTC check, check the circuit listed for that code. For details
of each code, refer to ºSee pageº under the respective DTC No. in the chart.
DTC No.
(See Page)Detection ItemTrouble Area
C1782/82
(DI±767)Stop light switch circuit malfunction

Stop light switch assy

Stop light switch circuit

Suspension control ECU
C1783/83
(DI±770)Door courtesy switch circuit malfunction

Door courtesy light switch assy

W/ Motor back door assy

Door courtesy light switch circuit

Body ECU

Back door ECU

Suspension control ECU
C1786/86
(DI±774)Height control switch circuit malfunction

Height control switch

Height control switch circuit

Suspension control ECU
C1788/88
(DI±778)Height control mode select switch circuit malfunction

Height control mode select switch

Height control mode select switch circuit

Suspension control ECU
2. INPUT SIGNAL CHECK (Using Hand±held Tester)
HINT:

This function checks if signals from the stop light switch
assy and the door courtesy lamp switch, etc. are being in-
put normally to the ECU.

When entering test mode, the suspension control ECU
sets all the test mode DTCs first.
After completing the test mode for each check item, the
test mode DTCs that are determined normal by the sus-
pension control ECU will be erased.
The test mode DTCs for other check items may not be
erased when only a certain signal is inspected.

When the test mode returns back to normal mode, all the
test mode DTCs will be erased.
(a) Procedure for Test Mode (Input signal check).
(1) Make sure that the ignition switch is off.
(2) Set each of the check items to the condition shown
under Operation (A) in the test mode table on the
next page.
(3) Connect the hand±held tester to the DLC3.
(4) Turn the ignition switch to the ON position.
(5) Select TEST MODE mode on the hand±held tester.
(6) Set each of the check items to the condition shown
under Operation (B) in the test mode table below.

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±715
909 Author: Date:
2005 SEQUOIA (RM1146U)
Test mode (input signal check) table:
Check ItemOperation (A)Operation (B)
Stop light switch signalOFF (Brake pedal not depressed)ON (Brake pedal depressed)
Door courtesy light switch signalON (Each door opened)OFF (All doors closed)
Height control switch signal±Press the height control switch ºUPº first and
then press ºDOWNº
Height control mode select switch signalOFF (Height control mode select switch not
pushed in)ON to OFF (Height control mode select switch
pushed in and released)
HINT:
In step (6), all signals can be checked together.
(7) Read the test mode DTCs by following the prompts
on the tester screen.
HINT:
Refer to the hand±held tester operator's manual for further de-
tails.
(8) Check the malfunction using the code table below.
DTC of air suspension system test mode (input signal check) function:
If a trouble code is displayed during the test mode DTC check, check the circuit listed for that code. For details
of each code, refer to ºSee pageº under the respective DTC No. in the chart.
DTC No.
(See Page)Detection ItemTrouble Area
C1782/82
(DI±767)Stop light switch circuit malfunction

Stop light switch assy

Stop light switch circuit

Suspension control ECU
C1783/83
(DI±770)Door courtesy switch circuit malfunction

Door courtesy light switch assy

W/ Motor back door assy

Door courtesy light switch circuit

Body ECU

Back door ECU

Suspension control ECU
C1786/86
(DI±774)Height control switch circuit malfunction

Height control switch

Height control switch circuit

Suspension control ECU
C1788/88
(DI±778)Height control mode select switch circuit malfunction

Height control mode select switch

Height control mode select switch circuit

Suspension control ECU
(9) After completing the test mode, disconnect the tes-
ter and turn the ignition switch off.

DIDCZ±01
DI±716
± DIAGNOSTICSAIR SUSPENSION SYSTEM
910 Author: Date:
2005 SEQUOIA (RM1146U)
PROBLEM SYMPTOMS TABLE
HINT:

If a normal system code is displayed during the DTC check but the problem still occurs, check the cir-
cuits for each problem symptom in the order given in the table below and proceed to the relevant trou-
bleshooting page.

Inspect the fuse before inspecting the suspected areas as shown in the chart below.

Inspect each malfunction circuit in numerical order for the corresponding symptom.

If the malfunction still exists even after checking and confirming that all the circuits are normal, replace
the suspension control ECU.
SymptomSuspected AreaSee page
Vehicle height control function does not operate.
If the compressor remains on for an excessive period of
time or turns on and off repeatedly, the system control will
be halted for up to 70 minutes, after which the system will
return to normal operation.
1. Air tube is seized
2. Power source circuit
3. IG signal circuit
4. Crankshaft position sensor circuit
5. Height control mode select switch circuit
6. Height control switch circuit
7. Height control sensor circuit
8. Leveling solenoid valve circuit
9. Gate solenoid valve circuit
10.Exhaust solenoid valve circuit
11. AIR SUS relay circuit
12.Height control compressor circuit
13.Suspension control ECU
±
DI±761
DI±793
DI±210
DI±778
DI±774
DI±731
DI±740
DI±736
DI±744
DI±747
DI±752
IN±35
Illuminated position of height control indicator lamp does not
change by the height control switch operation.
1. Power source circuit
2. Crankshaft position sensor circuit
3. Height control mode select switch circuit
4. Height control switch circuit
5. Height control sensor circuit
6. Leveling solenoid valve circuit
7. Gate solenoid valve circuit
8. Exhaust solenoid valve circuit
9. AIR SUS relay circuit
10.Height control compressor circuit
11. Speed sensor circuit
12.CAN communication circuit
13.Suspension control ECUDI±763
DI±761
DI±793
DI±210
DI±778
DI±774
DI±731
DI±740
DI±736
DI±744
DI±783
DI±1065
IN±35
Hunting of vehicle height occurs.
1. Air leakage (Height control cylinder assy rear)
2. Height control sensor circuit
3. Suspension control ECUSA±156
DI±731
IN±35
Vehicle height control operates, but vehicle height is uneven.
1. Air leakage
2. Clogging of the air tube
3. Height control sensor link sub±assy
4. Height control sensor circuit
5. Gate solenoid valve circuit
6. Suspension control ECUSA±156
±
SA±156
DI±731
DI±736
IN±35
Vehicle height control operates, but vehicle height is high or
low (Vehicle height in NORMAL mode differs from the standard
value).1. Height control sensor link sub±assy
2. Height control sensor circuit
3. Suspension control ECUSA±156
DI±731
IN±35
When vehicle height control is adjusted, it stops at extremely high
or low position.1. Height control sensor circuit
2. Height control sensor link sub±assy
3. Suspension control ECUDI±731
SA±156
IN±35

± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±717
911 Author: Date:
2005 SEQUOIA (RM1146U) Height control manual indicator lamp condition is abnormal.
1. Power source circuit
2. Height control mode select switch circuit
3. Height control manual indicator lamp circuit
4. Suspension control ECUDI±763
DI±778
DI±789
IN±35
Height control indicator lamp condition is abnormal.
1. Power source circuit
2. Height control indicator lamp circuit
3. Suspension control ECUDI±763
DI±785
IN±35
DTC check cannot be completed.
1. Power source circuit
2. CAN communication system
3. Height control manual indicator lamp circuit
4. Suspension control ECU
5. ECMDI±763
DI±782
DI±789
IN±35
IN±35
Input signal check (test mode) cannot be completed.
1. Power source circuit
2. CAN communication system
3. Suspension control ECU
4. Translate ECUDI±763
DI±783
IN±35
IN±35
Vehicle height is extremely low when vehicle is parked.
Although, especially in a cold district, the vehicle height
may become lower due to a drop in air temperature in the
height control cylinder assy, but this is not abnormal.
1. Air leakage
2. Height control cylinder assy
3. Height control sensor link sub±assy
4. Leveling solenoid valve circuit
5. Exhaust valve circuit
SA±156
±
SA±156
DI±740
DI±744
Compressor motor continues to operate.
Due to the air tube freezing, vehicle height may not rise.
1. Air leakage
2. Air tube clogged
3. Height control cylinder assy
4. Height control sensor link sub±assy
5. Height control sensor circuit
6. Leveling solenoid valve circuit
7. Exhaust valve circuit
8. AIR SUS relay circuit
9. Height control compressor circuit
10.Suspension control ECU
SA±156
±
±
SA±156
DI±731
DI±740
DI±744
DI±747
DI±752
IN±35

DIDD3±01
F16803
S25
DI±718
± DIAGNOSTICSAIR SUSPENSION SYSTEM
912 Author: Date:
2005 SEQUOIA (RM1146U)
TERMINALS OF ECU
Symbols (Terminal No.)Wiring ColorTerminal
DescriptionConditionSpecified Condition
SLEX (S25±1) ± LR WB
Exhaust Sole-
id V l Si
IG switch ON "
E i idli b tt f h i ht t l it h i h dBelow 1.0 V "SLEX (S25 1)
GND (S25±22)L±R ± W±Bnoid Valve Sig-
nalEngine idling, button of height control switch is pushed
from ºUPº to ºDOWNºBelow 1.0 V "
9 V or more
SLRR (S25±3) ± LG R W B
Leveling Sole-
id V l Si
IG switch ON "
E i idli b tt f h i ht t l it h i h dBelow 1.0 V "SLRR (S25 3)
GND (S25±22)LG±R ± W±Bnoid Valve Sig-
nalEngine idling, button of height control switch is pushed
from ºDOWNº to ºUPºBelow 1.0 V "
9 V or more
SLRL (S25±4) ± WL WBGate SolenoidIG switch ON "
E i idli b tt f h i ht t l it h i h dBelow 1.0 V "SLRL (S25 4)
GND (S25±22)W±L ± W±BGate Solenoid
Valve SignalEngine idling, button of height control switch is pushed
from ºDOWNº to ºUPºBelow 1.0 V "
9 V or more
RC (S25±5) ± GY WBAIR SUS RelayIG switch ON "
E i idli b tt f h i ht t l it h i h dBelow 1.0 V "RC (S25 5)
GND (S25±22)G±Y ± W±BAIR SUS Relay
SignalEngine idling, button of height control switch is pushed
from ºNº to ºUPºBelow 1.0 V "
9 V or more
HI (S25±8) ± GR R W B
Height Control
I di t ºHIº
Engine idling, vehicle height is ºNORMALº "
P i th ºUPº b tt f th t l it h t10 V or more "HI (S25 8)
GND (S25±22)GR±R ± W±BIndicator ºHIº
SignalPressing the ºUPº button of the control switch turns on
the ºHIº indicator lamp (*1)10 V or more "
Below 5 V
NR (S25±9) ± BL WB
Height Control
I di t ºNº
Engine idling, vehicle height is ºNORMALº "
P i th ºUPº b tt f th t l it h tBelow 5 V "NR (S25 9)
GND (S25±22)B±L ± W±BIndicator ºNº
SignalPressing the ºUPº button of the control switch turns on
the ºHIº indicator lamp (*1)Below 5 V "
10 V or more
IG (S25±10) ±
GND (S25±22)B±R ± W±BIgnition SwitchIG switch ON10 to 14 V
VN (S25±11) ± LG W B
Height Control
MlIdi
IG switch ON, height control manual indicator lamp ON
" Pressin
g and releasing the height control mode selectBelow 5 V "VN (S25 11)
GND (S25±22)LG ± W±BManual Indica-
tor Lamp Signal" Pressing and releasing the height control mode select
switch turns off the height control manual indicator lamp
(*1)
Below 5 V "
10 V or more
TD (S25±12) ± BR B W B
Height Control
Md Sl t
IG switch ON, height control mode select switch pushed
iBelow 1.5 V "TD (S25 12)
GND (S25±22)BR±B ± W±BMode Select
Switchin
" Height control select switch releasedBelow 1.5 V "
10 to 14 V
UPSW (S25±13) ± LB WB
Height Control
S it h ºUPº
IG switch ON, ºUPº button of height control switch
hdiBelow 1.5 V "UPSW (S25 13)
GND (S25±22)L±B ± W±BSwitch ºUPº
Signalpushed in "
ºUPº button of height control switch releasedBelow 1.5 V "
10 to 14 V
SBL (S25±15) ±
SGL (S25±19)G±O ± L±R
Height Control
Sensor Power
Source
IG switch ON4.5 to 5.5 V
SHRL (S25±17) ± GR L L R
Height Control
SIt
IG switch ON "
E i idli hi l h i ht i h d f ºHIGHº t0.5 to 4.5 V "SHRL (S25 17)
SGL (S25±19)GR±L ± L±RSensor Input
SignalEngine idling, vehicle height is changed from ºHIGHº to
ºNORMALº by pressing the height control switch0.5 to 4.5 V "
Approx. 2.5 V
SGL (S25±19) ±
GND (S25±22)L±R ± W±BHeight Control
Sensor GroundAlwaysBelow 1.0 V

DIDD7±01
C00083DLC3
± DIAGNOSTICSAIR SUSPENSION SYSTEM
DI±721
915 Author: Date:
2005 SEQUOIA (RM1146U)
DIAGNOSIS SYSTEM
1. DIAGNOSIS SYSTEM
(a) Inspect the battery voltage.
Battery voltage: 11 to 14 V
If voltage is below 11 V, recharge the battery before proceeding.
(b) Check DLC3.
The suspension control ECU uses the CAN system and
ISO 9141±2 for communication. The terminal arrange-
ment of the DLC3 complies with SAE J1962 and matches
the ISO 9141±2 format.
Verify the conditions listed in the table below:
Symbols (Terminal No.)Terminal DescriptionConditionSpecified Condition
SIL(7) ± SG(5)Bus º+º lineDuring communicationPulse generation
CG(4) ± Body groundChassis groundAlwaysBelow 1 W
SG(5) ± Body groundSignal groundAlwaysBelow 1 W
BAT(16) ± Body groundBattery positiveAlways11 to 14 V
CANH(6) ± CANL (14)HIGH±level CAN bus lineIG switch OFF54 to 67 W
CANH(6) ± Battery positiveHIGH±level CAN bus lineIG switch OFF1 MW or higher
CANH(6) ± CG(4)HIGH±level CAN bus lineIG switch OFF3 KW or higher
CANL(14) ± Battery positiveLOW±level CAN bus lineIG switch OFF1 MW or higher
CANL(14) ± CG(4)LOW±level CAN bus lineIG switch OFF3 KW or higher
HINT:
If the hand±held tester display shows UNABLE TO CONNECT
TO VEHICLE when the cable of the hand±held tester is con-
nected to the DLC3, the ignition switch is turned ON and the tes-
ter is operated, there is a problem on the vehicle side or tester
side.

If communication is normal when the tester is connected
to another vehicle, inspect the DLC3 on the original ve-
hicle.

If communication is still not possible when the tool is con-
nected to another vehicle, the problem is probably in the
tester itself, so consult the service department listed in the
tester 's instruction manual.
(c) DTCs (Normal mode)
(1) DTCs are memorized in the suspension control
ECU and read by using the SST check wire or the
hand±held tester (see page DI±723 for the proce-
dure of DTCs check).
SST 09843±18040
(d) Test mode (Input signal check)
(1) By switching from normal mode into test mode, you
can inspect the height control switch, height control
mode select switch, door courtesy lamp switch, and
stop lamp switch (see page DI±711).