fuse TOYOTA SEQUOIA 2001 Service User Guide

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 DI±88
± DIAGNOSTICSENGINE
282 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0031 Oxygen (A/F) Sensor Heater Control Circuit
Low (Bank 1 Sensor 1)
DTC P0032 Oxygen (A/F) Sensor Heater Control Circuit
High (Bank 1 Sensor 1)
DTC P0051 Oxygen (A/F) Sensor Heater Control Circuit
Low (Bank 2 Sensor 1)
DTC P0052 Oxygen (A/F) Sensor Heater Control Circuit
High (Bank 2 Sensor 1)
HINT:
Although each DTC title (DTC description) says ºoxygen sensorº, these DTCs are related to the ºA/F sensorº.
CIRCUIT DESCRIPTION
Refer to DTC P2195 on page DI±383.
HINT:
The ECM provides a pulse width modulated control circuit to adjust current through the heater. The A/F sen-
sor heater circuit uses a relay on the B+ side of the circuit.
DTC No.DTC Detection ConditionTrouble Area
P0031
P0051Heated current is 0.8 A or less when heater operates
(1 trip detection logic)
Open or short in heater circuit of A/F sensor

A/F sensor heater
P0032
P0052When the heater operates, heated current exceeds 19.7 A
(1 trip detection logic)
A/F sensor heater

A/F sensor heater relay

ECM
DIDFP±01

B17386
Housing
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Heater
Coating (Ceramic)
Exhaust Gas CoverIdeal Air±Fuel Mixture
Output Voltage
Richer ± Air Fuel Ratio ± Leaner
Atmospheric Air
A21040
Reference(Bank 1 Sensor 1 System Drawing) :
ECM
EFI Relay
EFI Fuse No. 1 From
Battery
GroundOX1A
MREL HT1A
Duty
Control Heater
Sensor Heated Oxygen Sensor
EFI Fuse No. 2
E2 DI±94
± DIAGNOSTICSENGINE
288 Author: Date:
2005 SEQUOIA (RM1146U)
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three±way cata-
lytic converter is used, but for the most efficient use of the three±way catalytic converter, the air±fuel ratio
must be precisely controlled so that it is always close to the stoichiometric air±fuel ratio.
The heated oxygen sensor has the characteristic which its output voltage changes suddenly in the vicinity
of the stoichiometric air±fuel ratio. This characteristic is used to detect the oxygen concentration in the ex-
haust gas and provide the ECM with feedback to control the air±fuel ratio.
When the air±fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the heated
oxygen sensor informs the ECM of the LEAN condition (low voltage, i.e. less than 0.45 V).
When the air±fuel ratio is RICHER than the stoichiometric air±fuel ratio, the oxygen concentration in the ex-
haust gas is reduced and the heated oxygen sensor informs the ECM of the RICH condition (high voltage,
i.e. more than 0.45 V). The ECM judges by the voltage output from the heated oxygen sensor whether the
air±fuel ratio is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the
heated oxygen sensor causes output of abnormal voltage, this disables the ECM for performing an accurate
air±fuel ratio control. The heated oxygen sensors include a heater which heats the zirconia element. The
heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is
low) current flows to the heater to heat the sensor for accurate oxygen concentration detection.
HINT:
The ECM provides a pulse width modulated control circuit to adjust current through the heater. The heated
oxygen sensor heater circuit uses a relay on the B+ side of the circuit.

A21375
Engine Room J/B:
EFI
No. 2 Fuse
A21226
Wire Harness Side:
Mass Air Flow Meter Connector
M1
+B
A21376
Engine Room J/B:
EFI Relay
DI±108
± DIAGNOSTICSENGINE
302 Author: Date:
2005 SEQUOIA (RM1146U)
5 Check for open and short in harness and connector between mass air flow meter
and EFI relay.
PREPARATION:
Remove the EFI No. 2 fuse from the engine room J/B.
CHECK:
Check the resistance in the EFI No. 2 fuse.
OK:
Standard:
Below 1 W
PREPARATION:
(a) Install the EFI No. 2 fuse.
(b) Disconnect the M1 mass air flow meter connector.
(c) Remove the EFI relay from the engine room J/B.
CHECK:
Check the resistance between the wire harness side connec-
tors.
OK:
Standard:
Tester ConnectionSpecified Condition
+B (M1±1) ± Engine Room J/B (EFI
relay terminal 1)Below 1 W
+B (M1±1) or Engine room J/B (EFI relay
terminal 1) ± Body ground10 kW or higher
NG Repair or replace harness or connector.
OK
Check ECM power source circuit
(See page DI±493).

A23543
+B
OXR2
OXL2E1 HTR2
HTL2
H2
H4
Wire Harness Side:
Bank 1 Sensor 2, Bank 2 Sensor 2
B17416HT1BECM Connector E7OX1B E8
HT2B
OX2B
A21040
Reference (Bank 1 Sensor 1 System Drawing)
From
BatteryEFI No. 1 FuseEFI Relay
EFI No. 2 FuseHeater Oxygen
Sensor
Heater
SensorHT1A
OX1A
E2
MRELECM
DI±164
± DIAGNOSTICSENGINE
358 Author: Date:
2005 SEQUOIA (RM1146U)
17 Check for open and short in harness and connector between ECM and heated
oxygen sensor.
PREPARATION:
(a) Disconnect the heated oxygen sensor connector.
(b) Disconnect the E7 and E8 ECM connector.
CHECK:
Measure the resistance between the wire harness side connec-
tors.
OK:
Standard:
Tester ConnectionSpecified Condition
OXL2 (H2±3) ± OX1B (E8±18)Below 1 W
HTL2 (H2±1) ± HT1B (E8±1)Below 1 W
OXR2 (H4±3) ± OX2B (E7±33)Below 1 W
HTR2 (H4±1) ± HT2B (E7±5)Below 1 W
OXL2 (H2±3) or OX1B (E8±18) ±
Body ground10 kW or higher
HTL2 (H2±1) or HT1B (E8±1) ±
Body ground10 kW or higher
OXR2 (H4±3) or OX2B (E7±33) ±
Body ground10 kW or higher
HTR2 (H4±1) or HT2B (E7±5) ±
Body ground10 kW or higher
NG Repair or replace harness or connector.
OK
Replace heated oxygen sensor.

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
DI±176
± DIAGNOSTICSENGINE
370 Author: Date:
2005 SEQUOIA (RM1146U)
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
NG Replace or replace harness or connector.
OK
14 Replace air fuel ratio sensor.
NEXT

± DIAGNOSTICSENGINE
DI±283
477 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0504 Brake Switch ºAº/ºBº Correlation
CIRCUIT DESCRIPTION
In addition to turning on the stop lamps, the stop lamp switch signals are used for a variety of engine, trans-
mission, and suspension functions as well as being an input for diagnostic checks. It is important that the
switch operates properly, therefore this switch is designed with two complementary signal outputs: STP and
ST1±. The ECM analyzes these signal outputs to detect malfunctions in the stop lamp switch.
HINT:
Normal condition is as shown in the table.
SignalBrake pedal releasedIn transitionBrake pedal depressed
STPOFFONON
ST1±ONONOFF
DTC No.DTC Detection ConditionTrouble Area
P0504
Conditions (a), (b) and (c) continue for 0.5 sec. or more:
(a) Ignition switch ON
(b) Brake pedal released
(c) STP signal is OFF when the ST1± signal is OFF
Short in stop lamp switch signal circuit

Stop lamp fuse

Stop lamp switch

ECM
DID8C±01

DI±292
± DIAGNOSTICSENGINE
486 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0560 System Voltage
MONITOR DESCRIPTION
The battery supplies electricity to the ECM even when the ignition switch is OFF. This electricity allows the
ECM to store data such as DTC history, freeze frame data, fuel trim values, and other data.
If the battery voltage falls below a minimum level, the ECM will conclude that there is a fault in the power
supply circuit. The next time the engine starts, the ECM will turn on the MIL and a DTC will be set.
DTC No.DTC Detecting ConditionTrouble Area
P0560Open in back up power source circuit

Open in back±up power source circuit

EFI fuse

ECM
HINT:
If DTC P0560 present, the ECM will not store another DTC.
MONITOR STRATEGY
Related DTCsP0560System voltage malfunction
Required sensors/componentsECM
Frequency of operationContinuous
Duration3 sec.
MIL operationImmediate (*1)
Sequence of operationNone
*1: The DTC is set immediate. The MIL will be illuminated after the engine starts in the next time.
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Stand±by RAMInitialized
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Battery voltageLess than 3.5 V
DICF7±02

A21381
Engine Room J/B
EFI No. 1 Fuse
B17411
BATT (+) E6
E4
E1(±)
DI±294
± DIAGNOSTICSENGINE
488 Author: Date:
2005 SEQUOIA (RM1146U)
2 Check EFI No. 1 fuse of engine room J/B.
PREPARATION:
Remove the EFI No. 1 fuse from the engine room J/B.
CHECK:
Check the resistance of the EFI No. 1 fuse.
OK:
Standard: Below 1 W
NG Check for short in all harness and components
connected to EFI No. 1 fuse.
OK
3 Check voltage between terminal BATT and E1 of ECM connector.
CHECK:
Measure the voltage between terminals of the E6 and E4 ECM
connector.
OK:
Standard:
Tester ConnectionSpecified Condition
BATT (E4±3) ± E1 (E6±1)9 to 14 V
OK Check for intermittent problems
(See page DI±11).
NG

A21381
Engine Room J/B
EFI No. 1 Fuse
B17417
E4
BATT ECM Connector
± DIAGNOSTICSENGINE
DI±295
489 Author: Date:
2005 SEQUOIA (RM1146U)
4 Check for open and short in harness and connector between ECM and EFI No. 1
fuse, EFI No. 1 fuse and battery.
PREPARATION:
(a) Remove the EFI No. 1 fuse from the engine room J/B.
(b) Disconnect the E4 ECM connector.
CHECK:
Measure the resistance between the wire harness side connec-
tor.
OK:
Standard:
Tester ConnectionSpecified Condition
Engine Room J/B (EFI No. 1 fuse
terminal 2) ± BATT (E4±3)Below 1 W
Engine Room J/B (EFI No. 1 fuse
terminal 2) or BATT (E4±3) ±
Body ground
10 kW or higher
NG Repair or replace harness or connector.
OK
5 Check the battery (See page CH±1).
NG Replace battery.
OK
Check and replace engine room J/B.

A21430
From BatteryETCS Fuse
+BM
+M
±M
ME01ECM
Motor Control
Circuit Throttle Control Motor
2
1 DI±362
± DIAGNOSTICSENGINE
556 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2118 Throttle Actuator Control Motor Current
Range/Performance
CIRCUIT DESCRIPTION
The Electronic Throttle Control System (ETCS) has a dedicated power supply circuit. The voltage (+BM) is
monitored and when the voltage is low (less than 4V), the ECM concludes that the ETCS has a fault and
current to the throttle control motor is cut.
When the voltage becomes unstable, the ETCS itself becomes unstable. For this reason, when the voltage
is low, the current to the motor is cut. If repairs are made and the system has returned to normal, turn the
ignition switch OFF. The ECM then allows current to flow to the motor and the motor can be restarted.
HINT:
This Electrical Throttle Control System (ETCS) does not use a throttle cable.
DTC No.DTC Detection ConditionTrouble Area
P2118Open in ETCS power source circuit (+BM)

Open in ETCS power source circuit

ETCS fuse

ECM
MONITOR DESCRIPTION
The ECM monitors the battery supply voltage applied to the electronic throttle motor +BM. When the power
supply voltage drops below the threshold, the ECM concludes that the power supply has an open circuit.
The MIL is turned on and a DTC is set.
DICFB±02