2001 TOYOTA SEQUOIA heater

+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±455
649 Author: Date:
2005 SEQUOIA (RM1146U)
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.
HINT:

DTC P2A00 may be also set, when the air±fuel ratio is stuck rich or lean.

A low A/F sensor voltage could be caused by a rich air±fuel mixture. Check for conditions that would
cause the engine to run rich.

A high A/F sensor voltage could be caused by a lean air±fuel mixture. Check for conditions that would
cause the engine to run lean.

Read freeze frame data using a hand±held tester or OBD II scan tool. Freeze frame data record the
engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help
determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air±fuel
ratio was lean or rich, and other data, from the time the malfunction occurred.

B17396
HT +B
AF± AF+ Sensor 1A/F Sensor Component Side:
Front View
DI±456
± DIAGNOSTICSENGINE
650 Author: Date:
2005 SEQUOIA (RM1146U)
1 Check any other DTCs output (in addition to DTC P2A00 or P2A03).
PREPARATION:
(a) Connect a 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 / DTC INFO / CURRENT CODES.
CHECK:
(a) Read DTCs.
Result:
Display (DTC Output)Proceed To
P2A00 and/or P2A03A
P2A00 and/or P2A03 and other DTCsB
HINT:
If any DTCs other than P2A00 and/or P2A03 are output, troubleshoot those DTCs first.
B Go to DTC chart (See page DI±58).
A
2 Check resistance of air±fuel ratio (A/F) sensor heater.
PREPARATION:
Disconnect the air±fuel ratio (A/F) sensor connector.
CHECK:
Measure resistance between the terminals of the A/F sensor
connector.
OK:
Standard:
Tester ConnectionSpecified Condition
HT (1) ± +B (2)Between 1.8 W and 3.4 W at 20C (68F)
HT (1) ± AF± (4)10 kW or higher
NG Replace air±fuel ratio (A/F) sensor.
OK

A23659
Wire Harness Side:
HT
A38
Sensor 1A/F Sensor Connector
AF+
Front ViewAF±
+B A39
B17415A55007
E7ECM Connector
HA1A
A1A+
A1A±
A2A+
A2A±HA2A
A23512
Reference (Bank 1 Sensor 1 System Drawing):
A/F Sensor A/F Relay
Heater
Sensor
A1A+ HA1A
Duty
Control ECM
From
Battery
A/F Heater
Fuse
A1A±
To EFI Relay
± DIAGNOSTICSENGINE
DI±457
651 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check for open and short in harness and connector between ECM and A/F sen-
sor.
PREPARATION:
(a) Disconnect the A38 or A39 A/F sensor connector.
(b) Turn the ignition switch to ON.
CHECK:
(a) Measure the voltage between the +B terminal of the A/F
sensor connector and body ground.
OK:
Standard:
Tester ConnectionsSpecified Conditions
+B (2) ± Body groundBetween 9 V and 14 V
PREPARATION:
(a) Turn the ignition switch to OFF.
(b) Disconnect the E7 ECM connector.
CHECK:
(a) Check the resistance.
OK:
Standard (Check for open):
Tester ConnectionsSpecified Conditions
HT (A38±1) ± HA1A (E7±2)
HT (A39±1) ± HA2A (E7±1)Below 1 W
AF+ (A38±3) ± A1A+ (E7±22)
AF+ (A39±3) ± A2A+ (E7±23)Below 1 W
AF± (A38±4) ± A1A± (E7±30)
AF± (A39±4) ± A2A± (E7±31)Below 1 W
Standard (Check for short):
Tester ConnectionsSpecified Conditions
HT (A38±1) or HA1A (E7±2) ± Body ground
HT (A39±1) or HA2A (E7±1) ± Body ground10 kW or higher
AF+ (A38±3) or A1A+ (E7±22) ± Body ground
AF+ (A39±3) or A2A+ (E7±23) ± Body ground10 kW or higher
AF± (A38±4) or A1A± (E7±30) ± Body ground
AF± (A39±4) or A2A± (E7±31) ± Body ground10 kW or higher

DIDIJ±01
± DIAGNOSTICSAUTOMATIC TRANSMISSION
DI±517
711 Author: Date:
2005 SEQUOIA (RM1146U)
TOYOTA PART AND SYSTEM NAME LIST
This reference list indicates the part names used in this manual along with their definitions.
Part and system nameDefinition
Toyota HCAC system, Hydrocarbon adsorptive Catalyst
(HCAC) system, HC adsorptive three±way catalystHC adsorptive three±way catalytic converter
Variable Valve Timing sensor, VVT sensorCamshaft position sensor
Variable valve timing system, VVT systemCamshaft timing control system
Camshaft timing oil control valve, Oil control valve OCV,
VVT, VSVCamshaft timing oil control valve
Variable timing and lift, VVTLCamshaft timing and lift control
Crankshaft position sensor ºAºCrankshaft position sensor
Engine speed sensorCrankshaft position sensor
THAIntake air temperature
Knock control moduleEngine knock control module
Knock sensorEngine knock sensor
Mass or volume air flow circuitMass air flow sensor circuit
Vacuum sensorManifold air pressure sensor
Internal control module, Control module, Engine control
ECU, PCMPower train control module
FC idleDeceleration fuel cut
Idle air control valveIdle speed control
VSV for CCV, Canister close valve VSV for canister controlEvaporative emissions canister vent valve
VSV for EVAP, Vacuum switching valve assembly No. 1,
EVAP VAV, Purge VSVEvaporative emissions canister purge valve
VSV for pressure switching valve, Bypass VSVEvaporative emission pressure switching valve
Vapor pressure sensor, EVAP pressure sensor, Evaporative
emission control system pressure sensorFuel tank pressure sensor
Charcoal canisterEvaporative emissions canister
ORVR systemOn±board refueling vapor recovery system
Intake manifold runner controlIntake manifold tuning system
Intake manifold runner valve, IMRV, IACV (runner valve)Intake manifold tuning valve
Intake control VSVIntake manifold tuning solenoid valve
AFSAir fuel ratio sensor
O2 sensorHeater oxygen sensor
Oxygen sensor pumping current circuitOxygen sensor output signal
Oxygen sensor reference ground circuitOxygen sensor signal ground
Accel position sensorAccelerator pedal position sensor
Throttle actuator control motor, Actuator control motor, Elec-
tronic throttle motor, Throttle control motorElectronic throttle actuator
Electronic throttle control system, Throttle actuator control
systemElectronic throttle control system
Throttle/pedal position sensor, Throttle/pedal position switch,
Throttle position sensor/switchThrottle position sensor
Turbo press sensorTurbocharger pressure sensor
Turbo VSVTurbocharger pressure control solenoid valve
P/S pressure switchPower±steering pressure switch
VSV for ACMActive control engine mount
Speed sensor, Vehicle speed sensor ºAº, Speed sensor for
skid control ECUVehicle speed sensor
ATF temperature sensor, Trans. fluid temp. sensor, ATF
temperature sensor ºAºTransmission fluid temperature sensor
Electronic controlled automatic transmission, ECTElectronically controlled automatic
Intermediate shaft speed sensor ºAºCounter gear speed sensor

DI±1484
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1678 Author: Date:
2005 SEQUOIA (RM1146U)
4 Check SRS warning light.
PREPARATION:
(a) Connect the connectors to the airbag sensor assembly.
(b) Connect the connectors to the steering wheel pad.
(c) Connect the connectors to the front passenger airbag assembly.
(d) w/ Side and curtain shield airbag:
Connect the connectors to the side airbag assembly LH and RH.
(e) w/ Side and curtain shield airbag:
Connect the connectors to the curtain shield airbag assembly LH and RH.
(f) Connect the connectors to the front seat outer belt LH and RH.
(g) Connect the negative (±) terminal cable to the battery, and wait for at least 2 seconds.
CHECK:
(a) Turn the ignition switch to the ON position, and wait for at least 6 seconds.
(b) Operate all components of the electrical system (defogger, wiper, headlight, heater blower, etc.) and
check the SRS warning light operation.
OK:
The SRS warning light does not come on.
NG Replace airbag sensor assembly
(see page RS±82).
OK
END

DI94R±07
I28393
Hood Courtesy Switch Engine Room J/B
 ECU±B Fuse
 Door No. 2 Fuse
 H±LP RH Fuse (*2)
 H±LP LH Fuse (*2)
 DRL Fuse (*1)
Rear Washer Motor
Horn
Headlight
Rear washer switch
Ignition Switch
 Key Unlock Switch
DLC3 Body ECU
Instrument Panel J/B
 ECU±IG Fuse
 RAD No. 2 Fuse
 FOG Fuse
 FOG LIGHT Relay
 POWER MAIN Relay
 WSH Fuse
 STOP Fuse
 TAILLIGHT Relay Back Door Power
Window SwitchTheft Horn
Engine Room R/B
No.2
 DIMMER Relay
 DRL No. 4 Relay
 H±LP RH Fuse (*1)
 H±LP LH Fuse (*1)
 H±LP RL Fuse (*1)
 H±LP LL Fuse (*1)
Fog Light
Wireless Door
Control Receiver Wireless Door Lock Buzzer
Combination Meter Memory Seat Switch
(*1): w/ Daytime Running Light
(*2): w/o Daytime Running Light (Located behind
the instrument panel)
(Located behind
the heater control panel)
 DOME Fuse
 HEAD Relay
 HORN Relay
 DOME Fuse
Automatic Light Control Sensor
Stop Light Switch
Remote Control Mirror SwitchGlass Breakage
Sensor Microphone Glass Breakage
Sensor ECU
Combination Switch
 Light Control Switch
 Headlight Dimmer Switch
 Fog Light Switch DI±1698
± DIAGNOSTICSBODY CONTROL SYSTEM
1892 Author: Date:
2005 SEQUOIA (RM1146U)
PARTS LOCATION

DIDFN±01
B78765I28978
Battery
Serial Communication Switch
ECUOn On
Off
ECULight
Motor
Heater
Solenoid
Conceptual Drawing 
I28977
Frame
Data
Header End Message
± DIAGNOSTICSMULTIPLEX COMMUNICATION SYSTEM
DI±1889
2083 Author: Date:
2005 SEQUOIA (RM1146U)
SYSTEM DESCRIPTION
Basic of MPX (Multiplex Communication)
1. General
The SEQUOIA multiplex communication system uses serial communication, which converts multiple pieces
of information into serial communication data. As a result, they can be transmitted through a single commu-
nication wire.
Serial communication data consists of bits and frames. A bit is the basic unit that represents the amount of
information. A bit is represented by a binary value º0º or º1º. A frame is a body of data that is transmitted
together. A frame contains a ºheaderº that indicates the beginning of the data and an ºend messageº that
indicates the end of the data.

DI±1966
± DIAGNOSTICSAUDIO SYSTEM
2160 Author: Date:
2005 SEQUOIA (RM1146U)
5. Identify the condition in which the noise occurs, and check the noise filter on the related part.
Condition in which noise occursNoise Source
Depressing the acceleration pedal increases the noise, and stopping the
engine stops the noise immediately.Generator
Noise occurs during A/C or the heater operation.Blower motor
Rapid acceleration while driving on an unpaved road or after the ignition
switch is turned on makes noise.Fuel pump
Pressing and then releasing the horn switch, and keeping pressing the horn
switch makes unusual noise.Horn
Quiet noise is heard while the engine is running, but stops with the engine.Ignition
Noise occurs synchronously with the turn signal flash.Flasher
Noise occurs during window washer operation.Washer
Noise occurs while the engine is running, and it continues even after the en-
gine stops.Engine coolant temperature sensor
Noise occurs during wiper operation.Wiper
Noise occurs when the brake pedal is depressed.Stop light switch
Others.Static electricity stored on the vehicle
Reference:

Make sure first that there is no noise from outside. Failing to do so makes the noise source detec-
tion difficult and leads to misdiagnosis.

The noise should be removed in descending order of loudness.

Tuning the radio so that no station is received wakes the noise more noticeable, making the rec-
ognition of the phenomenon easier.