2001 TOYOTA SEQUOIA battery

± DIAGNOSTICSENGINE
DI±89
283 Author: Date:
2005 SEQUOIA (RM1146U)
HINT:

Bank 1 refers to the bank that includes cylinder No.1.

Bank 2 refers to the bank that does not include cylinder No.1.

Sensor 1 refers to the sensor closest to the engine assembly.

Sensor 2 refers to the sensor farthest away from the engine assembly.
MONITOR DESCRIPTION
The ECM uses the Air±Fuel Ratio sensor (A/F sensor) information to regulate the air±fuel ratio close to the
stoichiometric ratio. This maximizes the catalytic converter's ability to purify exhaust gases. The sensor de-
tects oxygen levels in the exhaust gas and sends this signal to the ECM.
The inner surface of the sensor element is exposed to outside air. The outer surface of the sensor element
is exposed to exhaust gas. The sensor element is made of platinum coated zirconia and includes an inte-
grated heating element. The zirconia element generates a small voltage when there is a large difference in
the oxygen concentrations of the exhaust and the outside air. The platinum coating amplifies the voltage
generation. When heated, the sensor becomes very efficient. If the temperature of the exhaust is low, the
sensor will not generate useful voltage signals without supplemental heating. The ECM regulates the sup-
plemental heating using a duty±cycle approach to regulate the average current in the heater element. If the
heater current is out of the normal range, the sensor's output signals will be inaccurate and the ECM can
not regulate the air±fuel ratio properly.
When the heater current is out of the normal operating range, the ECM interprets this as a malfunction and
sets a DTC.
MONITOR STRATEGY
P0031A/F sensor heater (Bank 1) range check (Low
current)
RltdDTC
P0032A/F sensor heater (Bank 1) range check (High
current)
Related DTCs
P0051A/F sensor heater (Bank 2) range check (Low
current)
P0052A/F sensor heater (Bank 2) range check (High
current)
Rid / tMain sensors/componentsA/F sensor heaterRequired sensors/componentsRelated sensors/components±
Frequency of operationContinuous
Duration10 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
P0031, P0051 (Low current):
Battery voltage10.5 V±
A/F sensor heater duty ratio50%±
Time after engine start10 sec.±

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.

± DIAGNOSTICSENGINE
DI±95
289 Author: Date:
2005 SEQUOIA (RM1146U)DTC No.
DTC Detecting ConditionTrouble Area
P0037Heater current is 0.25 A or less when the heater operates with

Open in heater circuit of heated oxygen sensor

Heated ox
ygen sensor heaterP0037
P0057
Heater current is 0.25 A or less when the heater o erates with
more than 10.5 V positive battery voltage

Heated oxygen sensor heater

EFI relay

ECM
P0038
P0058When heater operates, heater current exceeds 2.0 A

Short in heater circuit of heated oxygen sensor

Heated oxygen sensor heater

EFI relay

ECM
HINT:

Bank 1 refers to bank that includes cylinder No. 1.

Bank 2 refers to bank that does not includes cylinder No. 1.

Sensor 1 refers to the sensor closer to the engine assembly.

Sensor 2 refers to the sensor farther away from the engine assembly.
MONITOR DESCRIPTION
The sensing portion of the heated oxygen sensor has a zirconia element which is used to detect oxygen
concentration in the exhaust. If the zirconia element is at the proper temperature and difference of the oxy-
gen concentration between the inside and outside surface of sensor is large, the zirconia element will gener-
ate voltage signals. In order to increase the oxygen concentration detecting capacity in the zirconia element,
the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor. When
current in the sensor is out of the standard operating range, the ECM interprets this as a fault in the heated
oxygen sensor and sets a DTC.
Example:
The ECM will set a high current DTC if the current in the sensor is more than 2.0 A when the heater is OFF.
Similarly, the ECM will set a low current DTC if the current is less than 0.3 A when the heater is ON.
MONITOR STRATEGY
P0037Rear HO2S heater (Bank 1) range check (Low
Current)
RltdDTC
P0038Rear HO2S heater (Bank 1) range check (High
Current)
Related DTCs
P0057Rear HO2S heater (Bank 2) range check (Low
Current)
P0058Rear HO2S heater (Bank 2) range check (High
Current)
Rid / tMain sensors/componentsHO2S heaterRequired sensors/componentsRelated sensors/componentsVehicle speed sensor (VSS)
Frequency of operationContinuous
Duration0.3 sec.
MIL operationImmediate
Sequence of operationNone

DI±96
± DIAGNOSTICSENGINE
290 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
P0037, P0057 (Low current):
Battery voltage10.5 V±
All heater is turned OFF and intrusive
heating is operated when the following
conditions are met
Condition (a) and (b)
(a) HeaterON
(b) Heater current±0.3 A
P0038, P0058 (High current):
Case 1:
Battery voltage10.5 V±
EngineRunning
StarterOFF
Intrusive heatingNot operating
Case 2:
Battery voltage10.5 V±
All heater is turned OFF and intrusive
heating is operated when the following
conditions are met
Condition (a) and (b)
(a) HeaterON
(b) Heater current2 A±
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
P0037, P0057 (Low current):
HO2S heater current during intrusive heatingLess than 0.3 A (when battery voltage is 10.5 V or more)
P0038, P0058 (High current):
Case 1:
HO2S heater current2 A or more
Case 2:
HO2S heater current during intrusive heatingMore than 2 A
COMPONENT OPERATING RANGE
ParameterStandard Value
HO2S heater current0.4 to 1 A (at idle, warmed±up engine and +B: 11 to 14 V)

A23550
Battery 2FECM
OX1B HT2B
OX2B 33 Y
AG±R 3 2
ERB±W
EDW±B
5
4
5 1
22J2
IG4
HTR2
NTL2 OXR2
E8
F10
Fusible Link
Block G±R
EC 2D112H6
2A2 EFI Relay
EFI No. 1
EFI No. 2
J/C
IA4
G±R
HT1B 8
5
18
E8 E7
E7 E4
G±R G±R14
IA4 B±W
OXL21 4
A G±R Engine Room J/B
J42
J/CA
B J5
J/CW±R
E8
E6 G±W
BR
BR
H4 Heated Oxygen Sensor
(Bank 2 Sensor 2)
H2 Heated Oxygen Sensor
(Bank 1 Sensor 2)
J16
28
1 (Shielded) B
E B
EB J42
J/C G±W G±W
E1B
GJ/C
E1 +B
+B
E1 E2 MREL
(Shielded)
CC
C
BR DI±98
± DIAGNOSTICSENGINE
292 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM

F10
Fusible
Link
Block
A23554
ECM
VG
E2G 8
E4
30
E8
29
E8 B±W R±W
2
B IA414
BatteryB 2F1 2D1 Engine Room J/B
EFI No. 1 EFI Relay
EFI No. 2
5
3
1
2 2H2A2G±R J2
J/C
A
B G±R
IG422
G±R
3 IA44B±W
J16
J/C
6B
W±B G±RA
A
J5
J/C
ED
+B
VG
MREL
M1
Mass Air Flow Meter
B±W
G±R
1
4
5 E2G DI±104
± DIAGNOSTICSENGINE
298 Author: Date:
2005 SEQUOIA (RM1146U)
COMPONENT OPERATING RANGE
ParameterStandard Value
Mass air flow meter voltage0.4 to 2.2 V
WIRING DIAGRAM

± DIAGNOSTICSENGINE
DI±143
337 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR STRATEGY
Related DTCsP0128Thermostat
Rid / t
Main sensors/componentsEngine coolant temperature sensor, Engine
cooling system, Thermostat
Required sensors/components
Related sensors/componentsIntake air temperature sensor, Vehicle speed
sensor
Frequency of operationOnce per driving cycle
Duration15 min.
MIL operation2 driving cycles
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Battery voltage11.0 V±
Throttle position learningCompleted
Either of the following conditions is metCondition 1 or 2
1. All of the following conditions are metCondition (a), (b) and (c)
(a) ECT at engine start ± IAT at engine
start±15 to 7C (±27 to 12.6F)
(b) ECT at engine start±10 to 56C (14 to 133F)
(c) IAT at engine start±10 to 56C (14 to 133F)
2. All of the following conditions are metCondition (a), (b) and (c)
(a) ECT at engine start ± IAT at engine
start±7C (12.6F)±
(b) ECT at engine start±56C (133F)
(c) IAT at engine start±10C (14F)±
Accumulated time that vehicle speed is 80
mph (128 km/h) or more±20 sec.
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Duration that both of following conditions 1 and 2 are met5 sec. or more
1. Estimated engine coolant temperature75C (167F) or more
2. Engine coolant temperature sensor outputLess than 75C (167F)
COMPONENT OPERATING RANGE
ParameterStandard Value
Engine coolant temperature sensor output value after warm
up75C (167F) or more

± DIAGNOSTICSENGINE
DI±151
345 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR STRATEGY
P0136
Heated rear oxygen sensor (Bank 1) output volt-
age (Output voltage)
P0136Heated rear oxygen sensor (Bank 1) impedance
(Low)
P0137
Heated rear oxygen sensor (Bank 1) output volt-
age (Low voltage)
P0137Heated rear oxygen sensor (Bank 1) impedance
(High)
P0138
Heated rear oxygen sensor (Bank 1) output volt-
age (High voltage)
RltdDTC
P0138Heated rear oxygen sensor (Bank 1) output volt-
age (Extremely high)
Related DTCs
P0156
Heated rear oxygen sensor (Bank 2) output volt-
age (Output voltage)
P0156Heated rear oxygen sensor (Bank 2) impedance
(Low)
P0157
Heated rear oxygen sensor (Bank 2) output volt-
age (Low voltage)
P0157Heated rear oxygen sensor (Bank 2) impedance
(High)
P0158
Heated rear oxygen sensor (Bank 2) output volt-
age (High voltage)
P0158Heated rear oxygen sensor (Bank 2) output volt-
age (Extremely high)
Rid / tMain sensors/componentsHeated rear oxygen sensorRequired sensors/componentsRelated sensors/componentsMass air flow meter
Frequency of operationOnce per driving cycle: Active air±fuel ratio control detection
Continuous: Others
Duration
20 sec.: Heated oxygen sensor output (Output voltage, High voltage, Low voltage)
30 sec.: Heated oxygen sensor impedance (Low)
90 sec.: Heated oxygen sensor impedance (High)
10 sec.: Heated oxygen sensor impedance (Extremely high)
MIL operation2 driving cycles Heated oxygen sensor output (Output voltage, High voltage, Low voltage)
Immediate: Heated oxygen sensor impedance (Low, High, Extremely high)
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
Heated oxygen sensor output voltage (Output voltage, High voltage and Low voltage):
Active air±fuel ratio controlExecuting
Active air±fuel ratio control being when all
of following conditions met±
Battery voltage11 V±
Engine coolant temperature75°C (167°F)±
IdleOFF
Engine RPM±3,200 rpm