2001 TOYOTA SEQUOIA fuel pressure

DID82±01
A20891
Mass Air Flow Sensor Crankshaft Position Sensor
Actual Valve TimingCorrection Target Valve Timing
Feedback
Duty Control ECM
Camshaft Timing
Oil Control
Valve (OCV)
Vehicle Speed Signal Engine Coolant Temp. Sensor Throttle Position Sensor
Camshaft Position Sensor
± DIAGNOSTICSENGINE
DI±73
267 Author: Date:
2005 SEQUOIA (RM1146U)
CIRCUIT INSPECTION
DTC P0010 Camshaft Position ºAº Actuator circuit
(Bank 1)
DTC P0020 Camshaft Position ºAº Actuator circuit
(Bank 2)
CIRCUIT DESCRIPTION
The Variable Valve Timing (VVT) system includes the ECM, the Oil Control Valve (OCV) and the VVT control-
ler. The ECM sends a target ºduty±cycleº control signal to the OCV. This control signal, applied to the OCV,
regulates the oil pressure supplied to the VVT controller. Camshaft timing control is performed based on en-
gine operation conditions such as intake air volume, throttle position and engine coolant temperature.
The ECM controls the OCV, based on the signals output from the sensors. The VVT controller regulates the
intake camshaft angle using oil pressure through the OCV. As a result, the relative position between the cam-
shaft and the crankshaft is optimized, and the engine torque improves, fuel economy improves, and exhaust
emissions decrease under overall driving conditions. Also, the ECM detects the actual valve timing using
signals from the camshaft position sensor and the crankshaft position sensor, and performs feedback con-
trol. This is how target valve timing is verified by the ECM.
DTC No.DTC Detecting ConditionTrouble Area
P0010
P0020Open or short in OCV circuit

Open or short in OCV circuit

OCV

ECM

+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.

A21341
+B
OX E1HT
H2
H4
Components Side:
Bank 1 Sensor 2, Bank 2 Sensor 2
DI±162
± DIAGNOSTICSENGINE
356 Author: Date:
2005 SEQUOIA (RM1146U)
check and repair extremely rich or lean actu-
arial air fuel ratio (injector, fuel pressure, gas
leakages from exhaust system, etc.)
14 Check for exhaust gas leakage.
CHECK:
Check for exhaust gas leakage from the exhaust manifold and pipe.
OK:
No exhaust gas leakage.
NG Repair or replace exhaust gas leakage point.
OK
15 Inspect heated oxygen sensor.
PREPARATION:
Disconnect the HO2 sensor connector.
CHECK:
Measure the resistance between the terminals of the HO2 sen-
sor connector.
OK:
Standard:
Tester ConnectionsSpecified Conditions
HT (2) ± +B (1)11 to 16 W at 20C (68F)
HT (2) ± E (3)10 kW or higher
NG Replace heated oxygen sensor.
OK

DI±166
± DIAGNOSTICSENGINE
360 Author: Date:
2005 SEQUOIA (RM1146U)DTC No.
DTC Detecting ConditionTrouble Area
P0171
P0174When air±fuel ratio feedback is stable after warming up the
engine, fuel trim is considered to be in error on LEAN side
(2 trip detection logic)

Air induction system

Injector blockage

Mass air flow meter

Engine coolant temperature sensor

Fuel pressure

Gas leakage in exhaust system

Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit

Heated oxygen sensor (bank 1, 2 sensor 1)

Heated oxygen sensor heater (bank 1, 2 sensor 1)

EFI relay

PCV piping

ECM
P0172
P0175When air±fuel ratio feedback is stable after warming up the
engine, fuel trim is considered to be in error on RICH side
(2 trip detection logic)

Injector leak, blockage

Mass air flow meter

Engine coolant temperature sensor

Ignition system

Fuel pressure

Gas leakage in exhaust system

Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit

Heated oxygen sensor (bank 1, 2 sensor 1)

ECM
HINT:

When DTC P0171 or P0174 is recorded, the actual air±fuel ratio is on the LEAN side. When DTC
P0172 or P0175 is recorded, the actual air±fuel ratio is on the RICH side.

If the vehicle runs out of fuel, the air±fuel ratio is LEAN and DTC P0171 or P0174 may be recorded.
The MIL then comes on.

If the total of the short±term fuel trim value and long±term fuel trim value is within
35 % (engine cool-
ant temperature is more than 75 C (167F)), the system is functioning normally.

+25 %
±12.5 %
More than 3.35 V
Less than 3.0 V
1
A/F Sensor (Sensor 1)
Output Voltage
Injection volume
Output voltage
HO2 Sensor (Sensor 2)
Output VoltageMain Suspected
Trouble Areas
OK
+25 %
±12.5 %
More than 3.35 V
Less than 3.0V
Injection volume
Output voltage
+25 %
±12.5 %
More than 0.55 V
Less than 0.4V
Injection volume
Output voltage
A/F sensor+25 %
±12.5 %
More than 0.55 V
Less than 0.4V
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
NG OK
OK
OK
Almost
no reaction
'
Almost
no reaction Almost
no reaction
Almost
no reaction
Case
2
3
4
A/F sensor circuit A/F sensor heater
HO2 sensor
HO2 sensor circuit HO2 sensor heater
(Air±fuel ratio extremely
lean or rich)Injector
Gas leakage from
exhaust system Fuel pressure
± DIAGNOSTICSENGINE
DI±169
363 Author: Date:
2005 SEQUOIA (RM1146U)
Standard:
Tester Display
(Sensor)Injection VolumesStatusVoltages
AFS B1S1 (AFS B2S1)
(A/F)+25 %RichLess than 3.0
AFS B1S1 (AFS B2S1)
(A/F)±12.5 %LeanMore than 3.35
O2S B1S2 (O2S B2S2)
(HO2)+25 %RichMore than 0.55
O2S B1S2 (O2S B2S2)
(HO2)±12.5 %LeanLess than 0.4
NOTICE:
The Air±Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2)
sensor has a maximum output delay of approximately 20 seconds.

Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs
of both the A/F and HO2 sensors.

To display the graph, select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD
II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2, and press the YES but-
ton and then the ENTER button followed by the F4 button.

± DIAGNOSTICSENGINE
DI±171
365 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check air induction system (See page SF±1).
CHECK:
Check the air induction system for vacuum leaks.
NG Repair or replace air induction system.
OK
4 Perform active test (A/F control).
(a) Connect the hand±held tester to the DLC3.
(b) Start the engine and turn the tester ON.
(c) Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
(d) On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST /
A/F CONTROL.
(e) Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT
button to change the fuel injection volume).
(f) Monitor the voltage outputs of A/F and HO2 sensors(AFS B1S1 (AFS B2S1) and O2S B1S2 (O2S
B2S2)) displayed on the tester.
HINT:

The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection
volume by 25 %.

Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard:
Tester Display
(Sensor)Injection VolumesStatusVoltages
AFS B1S1 (AFS B2S1)
(A/F)+25 %RichLess than 3.0
AFS B1S1 (AFS B2S1)
(A/F)±12.5 %LeanMore than 3.35
O2S B1S2 (O2S B2S2)
(HO2)+25 %RichMore than 0.55
O2S B1S2 (O2S B2S2)
(HO2)±12.5 %LeanLess than 0.4
Result:
Status
AFS B1S1
(AFS B2S1)Status
O2S B1S2
(O2S B2S2)A/F Condition and
A/F Sensor ConditionMisfiresSuspected Trouble AreasProceed To
Lean/RichLean/RichNormal''C
LeanLeanActual air±fuel ratio leanMay occur

PCV valve and hose

PCV hose connections

Injector blockage

Gas leakage from exhaust system

Air induction system

Fuel pressure

Mass Air Flow (MAF) meter

Engine Coolant Temperature (ECT)
sensor
A

DI±172
± DIAGNOSTICSENGINE
366 Author: Date:
2005 SEQUOIA (RM1146U)Rich
RichActual air±fuel ratio rich'

Injector leakage or blockage

Gas leakage from exhaust system

Ignition system

Fuel pressure

MAF meter

ECT sensor
A
LeanLean/RichA/F sensor malfunction'
A/F sensorB
RichLean/RichA/F sensor malfunction'
A/F sensorB
Lean: During A/F CONTROL, the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the
HO2 sensor output voltage (O2S) is consistently less than 0.4 V.
Rich: During A/F CONTROL, the AFS is consistently less than 3.0 V, and the O2S is consistently more than
0.55 V.
B Go to step 11.
C Go to step 15.
A
5 Read value of engine coolant temperature.
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to ON and turn the tester ON.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / COOLANT
TEMP.
CHECK:
(a) Read the COOLANT TEMP twice, when the engine is cold and also when warmed up.
Standard:
With cold engine: Same as ambient air temperature.
With warm engine: Between 75C and 95C (167F and 203F)
NG Replace engine coolant temperature sensor.
OK

± DIAGNOSTICSENGINE
DI±173
367 Author: Date:
2005 SEQUOIA (RM1146U)
6 Read value of mass air flow meter.
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to ON and turn the tester ON.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / MAF and
COOLANT TEMP.
(d) Allow the engine to idle until the COOLANT TEMP reaches 75C (167F) or more.
CHECK:
(a) Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.
Standard:
MAF while engine idling: Between 1.4 gm/s and 2.3 gm/s (shift position: N, A/C: OFF).
MAF at engine speed of 2,500 rpm: Between 5.4 gm/s and 7.9 gm/s (shift position: N, A/C: OFF).
NG Replace mass air flow meter.
OK
7 Check fuel pressure (See page SF±7).
CHECK:
Check the fuel pressure (high or low pressure).
NG Check and replace fuel pump, pressure regula-
tor, fuel pipe line and filter (See page SF±1).
OK
8 Check exhaust system for gas leakage.
OK:
No exhaust gas leakage.
NG Repair or replace exhaust gas leakage point.
OK