Page 311 of 4323

A19549
THA
E2ECM
2
1
Mass Air
Flow Meter Mass Air
Flow Meter
45
M1
THA E2
M1
B17441THA
E2
THA
E2ECM Mass Air Flow Meter
M1
E8
± DIAGNOSTICSENGINE
DI±117
311 Author: Date:
2005 SEQUOIA (RM1146U)
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the M1 mass air flow meter connector.
(b) Connect terminals 4 and 5 of the mass air flow meter wire
harness side connector.
(c) Turn the ignition switch ON.
(d) When using hand±held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / IN-
TAKE AIR.
CHECK:
Read the temperature value on the hand±held tester.
OK:
Standard: Temperature value: 1405C (2845F) or more
OK Confirm good connection at sensor. If OK, re-
place mass air flow meter.
NG
3 Check for open in harness or ECM.
PREPARATION:
(a) Connect terminals THA and E2 of the E8 ECM connector.
HINT:
Before checking, do a visual and contact pressure check for the
ECM connector.
(b) Turn the ignition switch ON.
(c) When using hand±held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / IN-
TAKE AIR.
CHECK:
Read the temperature value on the hand±held tester.
OK:
Standard: Temperature value: 1405C (2845F) or more
OK Repair or replace harness or connector.
NG
Confirm good connection at ECM. If OK, re-
place ECM (See page SF±80).
Page 315 of 4323
FI6448
ECM
5 V
THW E2
Engine Coolant Temp. Sensor
2
1G±Y
G±W
E1 E2
E8
E8
2821
± DIAGNOSTICSENGINE
DI±121
315 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
If DTCs related to different system that have terminal E2 as the ground terminal are output simulta-
neously, terminal E2 may have an open circuit.
Read freeze frame data using the hand-held tester. Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the
vehicle was running or stopped, if the engine was warmed up or not, if the air±fuel ratio was lean or
rich, as well as other data from the time when a malfunction occurred.
Page 317 of 4323

A19552
Engine Coolant
Temp. Sensor
2
1THW
E2ECM
E2
B17441
Engine Coolant
Temp. Sensor
ECM
E2 THW
E2
THW
E2
E8ECM Connector
± DIAGNOSTICSENGINE
DI±123
317 Author: Date:
2005 SEQUOIA (RM1146U)
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the E2 engine coolant temperature (ECT)
sensor connector.
(b) Connect terminals 1 and 2 of the engine coolant tempera-
ture sensor wire harness side connector.
(c) Turn the ignition switch ON.
(d) When using hand±held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the hand±held tester.
OK:
Standard: Temperature value: 1405C (2845F) or more
OK Confirm good connection at sensor. If OK, re-
place engine coolant temperature sensor.
NG
3 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the E2 engine coolant temperature sensor
connector.
(b) Connect terminals THW and E2 of the E8 ECM connector.
HINT:
Before checking, do a visual and contact pressure checks for
the ECM connector.
(c) Turn the ignition switch ON.
(d) When using hand±held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the OBD II scan tool or the
hand±held tester.
OK:
Standard: Temperature value: 1405C (2845F) or more
OK Repair or replace harness or connector.
NG
Page 322 of 4323

A19755A21037
Throttle Position Sensor ECM
Magnet
Magnet
IC No.2 IC No.1
VC
VTA1
E2 VTA2Throttle Position Sensor Output Voltage (V)
Fail Safe Angle
*1
Usable Range
Throttle Valve Opening Angle (deg)84 6
0 5
2.60
2.25
0.97
0.69
Throttle Valve Fully Opened
(Throttle Position expressed as percentage
(VTA1) 64 to 96%)
Fail Safe Angle 7°
(Throttle Position expressed as percentage
(VTA1) about 10 to 24%) Throttle Valve Fully Closed
(Throttle Position expressed as percentage
(VTA1) 10 to 20%)
*1:
VTA1 VTA2 DI±128
± DIAGNOSTICSENGINE
322 Author: Date:
2005 SEQUOIA (RM1146U)
CIRCUIT DESCRIPTION
HINT:
This Electrical Throttle Control System (ETCS) does not use a throttle cable.
This throttle position sensor is a non±contact type.
The throttle position sensor is mounted on the throttle body. It detects the opening angle of the throttle valve.
This sensor is electronically controlled and uses Hall±effect elements, so that accurate control and reliability
can be obtained. The throttle position sensor has 2 sensor elements / signal outputs: VTA1 and VTA2. VTA1
used to detect the throttle opening angle and VTA2 is used to detect malfunctions in VTA1. Voltage applied
to VTA1 and VTA2 change between 0 V and 5 V in proportion to the opening angle of the throttle valve. There
are several checks that the ECM performs to confirm proper operation of the throttle position sensor and
VTA1.
The ECM judges the current opening angle of the throttle valve from these signals input from terminals VTA1
and VTA2, and the ECM controls the throttle motor to make the throttle valve angle properly in response to
driver inputs.
Page 326 of 4323
A19212
T14
Throttle Control Motor
and Position Sensor
4
6
1
2G±W
G±B
P±L
B±Y28
23
19
20
4
5
17 E8
P
VECM
E2
VC
VTA2
VTA1 3
5
(Shielded)
L±RM±
M+
GE01 E8
E8
E8
E8
E8
E8 DI±132
± DIAGNOSTICSENGINE
326 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
If DTCs related to different system that have terminal E2 as the ground terminal are output simulta-
neously, terminal E2 may have an open circuit.
Read freeze frame data using the hand-held tester. Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the
vehicle was running or stopped, if the engine was warmed up or not, if the air±fuel ratio was lean or
rich, as well as other data from the time when a malfunction occurred.
Page 329 of 4323
B17411
E2 VC
E8ECM Connector
± DIAGNOSTICSENGINE
DI±135
329 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check voltage between terminals VC and E2 of ECM connector.
PREPARATION:
(a) Disconnect the T14 throttle control motor and sensor con-
nector.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between the specified terminals of the E8
ECM connector.
OK:
Standard:
Tester ConnectionSpecified Condition
VC (E8±23) ± E2 (E8±28)4.5 to 5.5 V
NG Replace ECM (See page SF±80).
OK
4 Replace throttle body (See page SF±42).
Go
5 Check if DTC output recur.
PREPARATION:
(a) Clear the DTC (See page DI±43).
(b) Start the engine.
(c) Run the engine at idle for 15 seconds or more.
CHECK:
Read the DTC.
RESULT:
Display (DTC Output)Proceed to
ºP0120, P0122, P0123, P0220, P0222, P0223 and/or P2135º are output
againA
No DTC outputB
B System is OK.
A
Page 350 of 4323

+25 %
±12.5 %
More than 0.5 V
Less than 0.4 V
Case 1
Case 2
Case 3
Case 4
Output voltage of A/F sensor
(sensor 1: front sensor)
Injection volume
Output voltage
Output voltage of heated oxygen
sensor (sensor 2: rear sensor)Mainly suspected
trouble area
OK
+25 %
±12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
+25 %
±12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
Sensor 1: front sensor
(sensor 1, heater, sensor 1
circuit)
+25 %
±12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NGExtremely rich or lean actual
air±fuel ratio
(Injector, fuel pressure, gas
leakage in exhaust system,
etc.) OK
OK
OK
Almost
no reaction
'
Sensor 2: rear sensor
(sensor 2, heater, sensor 2
circuit)
Almost
no reactionAlmost
no reactionAlmost
no reaction
DI±156
± DIAGNOSTICSENGINE
350 Author: Date:
2005 SEQUOIA (RM1146U)
The following A/F CONTROL procedure enables the technician to check and graph the voltage output of
the heated oxygen sensors.
For displaying the graph indication, first enter ºACTIVE TEST / A/F CONTROL / USER DATA,º then select
ºA/F B1,2S1and O2S B1,2S2º by pressing ºYESº button, and push ºENTERº button before pressing ºF4º
button.
HINT:
If different DTCs that are related to different system are output simultaneously while terminal E2 is used
as a ground terminal, terminal E2 may be open.
Read freeze frame data using the hand-held tester. Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle
was running or stopped, the engine was warmed up or not, the air±fuel ratio was lean or rich, etc. when
a malfunction occurred.
Page 352 of 4323

B17416HT1BECM Connector
E7OX1B E8
HT2B
OX2B
A21341
+B
OX E1HT
H2
H4
Components Side:
Bank 1 Sensor 2, Bank 2 Sensor 2
DI±158
± DIAGNOSTICSENGINE
352 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check for short in harness and connector between terminal OX1B and HT1B,
OX2B and HT2B of ECM.
PREPARATION:
(a) Turn the ignition switch to OFF and wait for 5 minutes.
(b) Disconnect the E7 and E8 ECM connector.
CHECK:
(a) Check the resistance.
OK:
Standard:
Tester ConnectionsSpecified Conditions
HT1B (E8±1) ± OX1B (E8±18)10 kW or higher
HT2B (E7±5) ± OX2B (E5±33)10 kW or higher
OK Replace ECM (See page SF±80
NG
4 Check resistance of heated oxygen sensor heater.
PREPARATION:
Disconnect the heated oxygen sensor connector.
CHECK:
Measure resistance between terminals of the heated oxygen
sensor.
OK:
Standard:
Tester ConnectionSpecified Condition
HT (1) ± +B (2)11 to 16 W at 20°C (68°F)
+B (2) ± OX (3)10 kW or higher
NG Replace heated oxygen sensor.
OK
Repair or replace harness or connector.
5 Perform confirmation driving pattern.
NEXT