2001 TOYOTA SEQUOIA heating

± 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.±

± 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)

B17411
ECM Connector
E1AIDI
A16555
AIR INJ CHECK
AIR PUMP............................ON
EASV ............................OPEN
ASV1. .............................OPEN
ASV2...............................OPEN
A/F BANK1.......................19.05
A/F BANK2.......................19.05
PRESSURE....................17 kPa
PULSATION..............25.39 kPa
AI STATUS...........................OK
Remaining Time 05 sec.
Press [EXIT] to quit
Example: 80% Duty Signal5 V/DIV.
GND
20 ms/DIV.
± DIAGNOSTICSENGINE
DI±237
431 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:
The diagnostic information output from the AID can be confirmed by connecting an oscilloscope to the diag-
nostic information terminal of the AID. It narrows the trouble area to read the waveform on the oscilloscope
when performing the AI system intrusive operation function provided in the SYSTEM CHECK.
(1) Start the engine and warm it up.
(2) Turn the ignition switch to OFF.
(3) Connect a hand±held tester to the DLC3.
(4) Connect an oscilloscope probe to the AIDI terminal
of the ECM.
(5) Start the engine and turn the tester ON.
(6) On the tester, select the following menu items:
DIAGNOSIS / ENHANCED OBD II / SYSTEM
CHECK / AIR INJ CHECK / MANUAL OPERATION
/ OPERATION 1 and 2.
HINT:
OPERATION 1: AP: OFF, EASV:CLOSE, ASV1:CLOSE,
ASV2:CLOSE
OPERATION 2: AP: ON, EASV:OPEN, ASV1:OPEN,
ASV2:OPEN
(7) Monitor the voltage output of the AID (duty ratio sig-
nal).
Oscilloscope range:
ItemsContents
TerminalsCH1: AIDI ± E1
Equipment Settings5 V/Division, 20 to 40 ms/Division
ConditionsIdling
NOTICE:

This AIR INJECTION CHECK only allows technicians to operate the AI system for 5 seconds.
Furthermore, the check can be performed 4 times a trip. If the test is repeated, intervals of at
least 30 seconds are required between checks.
While the AI system operation using the hand±held tester is prohibited, the tester displays the
prohibition (WAIT or ERROR). If the ERROR (AI STATUS NG) is displayed on the tester, stop the
engine for 10 minutes and then try again.

Performing the AIR INJ CHECK over and over again may cause the damage in the secondary
air injection system. If necessary, put an interval of several minutes between tests to prevent
overheating the system.

B17411
ECM Connector
E1AIDI
A16555
AIR INJ CHECK
AIR PUMP............................ON
EASV ............................OPEN
ASV1. .............................OPEN
ASV2...............................OPEN
A/F BANK1.......................19.05
A/F BANK2.......................19.05
PRESSURE....................17 kPa
PULSATION..............25.39 kPa
AI STATUS...........................OK
Remaining Time 05 sec.
Press [EXIT] to quit
Example: 80% Duty Signal5 V/DIV.
GND
20 ms/DIV. DI±244
± DIAGNOSTICSENGINE
438 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:
The diagnostic information output from the AID can be confirmed by connecting an oscilloscope to the diag-
nostic information terminal of the AID. It narrows the trouble area search to read the waveform on the oscillo-
scope when performing the AI system intrusive operation function provided in the SYSTEM CHECK.
(1) Start the engine and warm it up.
(2) Turn the ignition switch to OFF.
(3) Connect a hand±held tester to the DLC3.
(4) Connect an oscilloscope probe to the AIDI terminal
of the ECM.
(5) Start the engine and turn the tester ON.
(6) On the tester, select the following menu items:
DIAGNOSIS / ENHANCED OBD II / SYSTEM
CHECK / AIR INJ SYSTEM.
(7) On the tester, select the following menu items:
DIAGNOSIS / ENHANCED OBD II / SYSTEM
CHECK / AIR INJ CHECK / MANUAL OPERATION
/ OPERATION 1 and 2.
HINT:
OPERATION 1: AP: OFF, EASV:CLOSE, ASV1:CLOSE,
ASV2:CLOSE
OPERATION 2: AP: ON, EASV:OPEN, ASV1:OPEN,
ASV2:OPEN
(8) Monitor the voltage output of the AID (duty ratio sig-
nal).
Oscilloscope range:
ItemsContents
TerminalsCH1: AIDI ± E1
Equipment Settings5 V/Division, 20 to 40 ms/Division
ConditionsIdling
NOTICE:

This AIR INJECTION CHECK only allows technicians to operate the AI system for 5 seconds.
Furthermore, the check can be performed 4 times a trip. If the test is repeated, intervals of at
least 30 seconds are required between checks.
While the AI system operation using the hand±held tester is prohibited, the tester displays the
prohibition (AI STATUS NG) or ERROR. At this time stop the engine for 10 minutes and then try
again.

Performing the AIR INJ CHECK over and over again may cause the damage in the secondary
air injection system. If necessary, put an interval of several minutes between tests to prevent
overheating the system.

Example: 80% Duty Signal5 V/DIV.
GND
20 ms/DIV. DI±346
± DIAGNOSTICSENGINE
540 Author: Date:
2005 SEQUOIA (RM1146U)
(1) Monitor the voltage output of the AID (duty ratio sig-
nal).
Oscilloscope range:
ItemsContents
TerminalsCH1: AIDI ± E1
Equipment Settings5 V/Division, 20 to 40 ms/Division
ConditionsIdling
NOTICE:

This AIR INJECTION CHECK only allows technicians to operate the AI system for 5 seconds.
Furthermore, the check can be performed 4 times a trip. If the test is repeated, intervals of at
least 30 seconds are required between checks.
While the AI system operation using the hand±held tester is prohibited, the tester displays the
prohibition (WAIT or ERROR). If the ERROR (AI STATUS NG) is displayed on the tester, stop the
engine for 10 minutes and then try again.

Performing the AIR INJ CHECK over and over again may cause the damage in the secondary
air injection system. If necessary, put an interval of several minutes between tests to prevent
overheating the system.

± DIAGNOSTICSENGINE
DI±405
599 Author: Date:
2005 SEQUOIA (RM1146U) Time after A/F sensor heating
20 sec.±
Battery voltage10.5 V±
Ignition switchON
Others:
Battery voltage10.5 V±
Ignition switchON
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
P2238, P2241 (A/F sensor open circuit between AF+ and AF±):
A/F sensor admittanceBellow 0.022 1/ohm
P2238, P2241 (A/F sensor short circuit between AF+ and GND):
A/F+ terminal voltage0.5 V or less
P2238, P2241 (A/F sensor short circuit between AF+ and AF±):
Difference between A/F+ terminal and AF± terminal voltage0.1 V or less
P2239, P2242 (A/F sensor short circuit between AF+ and +B):
A/F+ terminal voltageMore than 4.5 V
P2252, P2255 (A/F sensor short circuit between AF± and GND):
A/F± terminal voltage0.5 V or less
P2253, P225+ (A/F sensor short circuit between AF± and +B):
A/F± terminal voltageMore than 4.5 V
WIRING DIAGRAM
Refer to DTC P2195 on page DI±383.
INSPECTION PROCEDURE
HINT:
Hand±held tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE
TEST. The A/F CONTROL function can help to determine whether the Air±Fuel Ratio (A/F) sensor, Heated
Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using a hand±held tester.
(1) Connect a hand±held tester to the DLC3.
(2) Start the engine and turn the tester ON.
(3) Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
(4) On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE
TEST / A/F CONTROL.
(5) 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).
(6) Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 (AFS B2S1) and OS2 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.

AC2810
DIDKM±01
AC2811
N11084
Wrong Okay
HI LO HILO
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±2297
2491 Author: Date:
2005 SEQUOIA (RM1146U)
AIR CONDITIONING SYSTEM
PRECAUTION
1. DO NOT HANDLE REFRIGERANT IN AN ENCLOSED
AREA OR NEAR AN OPEN FLAME
2. ALWAYS WEAR EYE PROTECTION
3. BE CAREFUL NOT TO GET LIQUID REFRIGERANT IN
YOUR EYES OR ON YOUR SKIN
If liquid refrigerant gets in your eyes or on your skin:
(a) wash the area with lots of cool water.
CAUTION:
Do not rub your eyes or skin.
(b) apply clean petroleum jelly to the skin.
(c) go immediately to a hospital or see a physician for profes-
sional treatment.
4. NEVER HEAT CONTAINER OR EXPOSE IT TO NAKED
FLAME
5. BE CAREFUL NOT TO DROP CONTAINER OR APPLY
PHYSICAL SHOCKS TO IT
6. DO NOT OPERATE COMPRESSOR WITHOUT
ENOUGH REFRIGERANT IN REFRIGERATION SYS-
TEM
If there is not enough refrigerant in the refrigerant system, oil lu-
brication will be insufficient and compressor burnout may occur.
Necessary care should be taken to avoid this.
7. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE
WHILE COMPRESSOR IS OPERATE
Open and close only the low pressure valve. If the high pressure
valves are opened, refrigerant flows in the reverse direction
causing the charging cylinder to rupture.
8. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH
REFRIGERANT
If refrigerant is overcharged, it causes problems such as insuffi-
cient cooling, poor fuel economy, engine overheating etc.