2001 TOYOTA SEQUOIA DLC3 Ts

± DIAGNOSTICSENGINE
DI±157
351 Author: Date:
2005 SEQUOIA (RM1146U)
1 Read output DTC.
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the hand±held tester main switch ON.
(c) When using hand±held tester, enter the following menu: DIAGNOSIS / ENHANCED OBD II / DTC
INFO / CURRENT CODES.
CHECK:
Read the DTC using the hand±held tester.
RESULT:
Display (DTC Output)Proceed to
P0138, P0158A
P0137, P0157B
P0136, P0156C
HINT:
If any other codes besides P0136, P0137, P0138, P0156, P0157 and/or P0158 are output, perform the trou-
bleshooting for those DTCs first.
B Go to step 14.
C Go to step 7.
A
2 Check output voltage of heated oxygen sensor.
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) After warming up the engine, run the engine at 2,500 rpm for 3 minutes.
(c) When using hand±held tester, enter the following menu: DIAGNOSIS / ENHANCED OBD II / DATA
LIST / ALL / O2S B1S2 or B2S2.
(d) Allow the engine to idle.
CHECK:
Read the Heated Oxygen (HO2) sensor output voltage while idling.
RESULT:
HO2 Sensor Output VoltagesProceed To
More than 1.2 VA
Less than 1.0 VB
B Go to step 5.
A

± DIAGNOSTICSENGINE
DI±159
353 Author: Date:
2005 SEQUOIA (RM1146U)
6 Check whether DTC output recurs (DTC P0138, P0158)
CHECK:
(a) On the hand±held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC
INFO / CURRENT CODES.
(b) Read DTCs.
RESULT:
Display (DTC Output)Proceed To
P0138 or P0158A
No outputB
B Check for intermittent problems
(See page DI±11).
A
Replace heated oxygen sensor.
7 Check output voltage of heated oxygen sensor.
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to ON and turn the tester ON.
(c) Start the engine.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / O2S B1S2.
(e) After warming up the engine, run the engine at an engine speed of 2,500 rpm for 3 minutes.
CHECK:
(a) Read the output voltage of the HO2 sensor when the engine rpm is suddenly increased.
HINT:
Quickly accelerate the engine to 4,000 rpm 3 times using the accelerator pedal.
Standard: Fluctuates between 0.4 V or less and 0.5 V or more.
NG Go to step 14.
OK
8 Perform confirmation driving pattern.
NEXT

B17391
+12 %
Normal Malfunction±12 %
0 V 3.3 V
1 VA/F Sensor Output
HO2 Sensor OutputInjection Volume
Malfunction
± DIAGNOSTICSENGINE
DI±161
355 Author: Date:
2005 SEQUOIA (RM1146U)
13 Perform active test (injection volume).
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) Start the engine and turn the tester ON.
(c) Warm up the engine.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / INJ VOL.
CHECK:
(a) Change the fuel injection volume using the tester, monitoring the voltage output of Air±Fuel Ratio (A/F)
and HO2 sensors displayed on the tester.
HINT:

Change the fuel injection volume within the range of ±12 % and +12 %. The injection volume can be
changed in 1 % graduations within the range.

The A/F sensor is displayed as AFS B1S1 (AFS B2S1), and the HO2 sensor is displayed as O2S B1S2
(O2S B2S2), on hand±held testers.
RESULT:
Tester Display (Sensor)Voltage VariationsProceed To
AFS B1S1 (AFS B2S1) (A/F)Alternates between more and less than 3.3 VOK
AFS B1S1 (AFS B2S1) (A/F)Remains at more than 3.3 VNG
AFS B1S1 (AFS B2S1) (A/F)Remains at less than 3.3 VNG
HINT:
A normal HO2 sensor voltage (O2S B1S2 (O2S B2S2)) reacts in accordance with increases and decreases
in fuel injection volumes. When the A/F sensor voltage remains at either less or more than 3.3 V despite the
HO2 sensor indicating a normal reaction, the A/F sensor is malfunctioning.
NG Replace air±fuel ratio (A/F) sensor.
OK

DI±168
± DIAGNOSTICSENGINE
362 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
Battery voltage11 V±
Fuel system statusClosed±loop
Throttle position learningCompleted
Either of the following conditions is met:Condition 1 or 2
1. Engine RPM±1,000 rpm
2. Intake air amount per revolution0.26 g/sec.±
Catalyst monitorNo executed
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Purge±cutExecuting
Either of the following conditions is metCondition 1 or 2
1. Average between short±term fuel trim and long±term fuel
trim35% or more (varies with ECT)
2. Average between short±term fuel trim and long±term fuel
trim±35% or less (varies with ECT)
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.

DI±170
± DIAGNOSTICSENGINE
364 Author: Date:
2005 SEQUOIA (RM1146U)
HINT:

Read freeze frame data using a hand±held tester. 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.

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.
1 Check any other DTCs output (in addition to DTC P0171, P0172, P0174 or P0175).
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
P0171, P0172, P0174 or P0175A
P0171, P0172, P0174 or P0175 and other DTCsB
HINT:
If any DTCs other than P0171, P0172, P0174 or P0175 are output, troubleshoot those DTCs first.
B Go to DTC chart (See page DI±58).
A
2 Check connection of PCV piping.
OK:
PCV hose is connected correctly and is not damaged.
NG Repair or replace PCV piping.
OK

± 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