Inspection Procedure

WARNING: This page is about a different car, the 2007 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

Intelligent 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 the intelligent tester.

Connect the intelligent tester to the DLC3.
Start the engine and turn the tester ON.
Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
On the tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
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).
Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and 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 in the fuel injection volume.

Standard:

VOLTAGE STATUS

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1S1 or AFS B2S1 (A/F)	+25%	Rich	Less than 3.0
AFS B1S1 or AFS B2S1 (A/F)	-12.5%	Lean	More than 3.35
O2S B1S2 or O2S B2S2 (HO2)	+25%	Rich	More than 0.55
O2S B1S2 or O2S B2S2 (HO2)	-12.5%	Lean	Less than 0.4

NOTE: 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.

Fig 1: Air Fuel Ratio (A/F) And Heated Oxygen (HO2) Sensor Output Voltage Chart With Trouble Area

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2. Then press the YES button and ENTER button, followed by the F4 button.

HINT:

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0171, P0172, P0174, P0175)

Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
Turn the ignition switch ON and turn the intelligent tester ON.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
Read the DTCs.

Result

RESULT CHART

Display (DTC output)	Proceed to
P0171, P0172, P0174 or P0175	A
P0171, P0172, P0174 or P0175 and other DTCs	B

HINT:

If any DTCs other than P0171, P0172, P0173, P0174 and P0175 are output, troubleshoot those DTCs first.

B: GO TO DTC CHART

A: GO TO Next Step

CHECK CONNECTION OF VENTILATION HOSE
OK: Ventilation hose is connected correctly and is not damaged.

NG: REPAIR OR REPLACE VENTILATION HOSE

OK: GO TO Next Step
CHECK AIR INDUCTION SYSTEM
1. Check the air induction system for vacuum leaks.
  OK: No leakage from air induction system.
NG: REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK: GO TO Next Step

PERFORM ACTIVE TEST BY INTELLIGENT TESTER (A/F CONTROL)

Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
Start the engine and turn the tester ON.
Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
On the tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
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.)
Monitor the outputs of A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and 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 in the fuel injection volume.

Standard:

VOLTAGE STATUS

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1S1 or AFS B2S1 (A/F)	+25%	Rich	Less than 3.0
AFS B1S1 or AFS B2S1 (A/F)	-12.5%	Lean	More than 3.35
O2S B1S2 or O2S B2S2 (HO2)	+25%	Rich	More than 0.55
O2S B1S2 or O2S B2S2 (HO2)	-12.5%	Lean	Less than 0.4

Result

RESULT CHART

Status AFS B1S1 or AFS B2S1	Status O2S B1S2 or O2S B2S2	A/F Condition and A/F Sensor Condition	Misfires	Suspected Trouble Area	Proceed to
Lean/Rich	Lean/Rich	Normal	-	-	C
Lean	Lean	Actual air fuel ratio lean	May occur	Ventilation valve and hose Ventilation 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
Rich	Rich	Actual air fuel ratio lean	-	Injector leakage or blockage Gas leakage from exhaust system Injection system Fuel pressure MAF meter ECT sensor	A
Lean	Lean/Rich	A/F sensor malfunction	-	A/F sensor	B
Rich	Lean/Rich	A/F sensor malfunction	-	A/F sensor	B

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.

Lean/Rich: During A/F CONTROL of the ACTIVE TEST, the output voltage of the heated oxygen sensor alternates correctly.

B: GO TO step 11

C: GO TO step 15

A: GO TO Next Step

READ VALUE OF INTELLIGENT TESTER (COOLANT TEMP)
1. Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
2. Turn the ignition switch ON and turn the tester ON.
3. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY.
4. Read the COOLANT TEMP value when the engine is cold and warmed-up.
  Standard:
ECT when the engine is cold: Same as ambient temperature

ECT when the engine is warmed-up: 75 to 95°C (167 to 203°F)

NG: REPLACE ENGINE COOLANT TEMPERATURE SENSOR

OK: GO TO Next Step
READ VALUE OF INTELLIGENT TESTER (MAF)
1. Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
2. Turn the ignition switch ON and turn the tester ON.
3. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF and COOLANT TEMP.
4. Allow the engine to idle until the COOLANT TEMP reaches 75°C (167°F) or more.
5. Read the MAF with the engine in an idling condition and at an engine speed of 2, 500 rpm.
  Standard:
MAF at idle rpm: 4.0 to 8.0 g/sec. (shift lever is in N position and A/C is OFF)

MAF at 2,500 rpm: 10.0 to 20.0 g/sec. (shift lever is in N position and A/C is OFF)

NG: REPLACE MASS AIR FLOW METER

OK: GO TO Next Step
CHECK FUEL PRESSURE
Check the fuel pressure (see ON-VEHICLE INSPECTION ).

NG: REPAIR OR REPLACE FUEL SYSTEM

OK: GO TO Next Step
CHECK FOR EXHAUST GAS LEAKAGE
OK: No gas leakage.

NG: REPAIR OR REPLACE EXHAUST SYSTEM

OK: GO TO Next Step
CHECK FOR SPARK AND IGNITION
HINT:

If the spark plugs or ignition system malfunction, engine misfire may occur. The misfire counter can be read with the intelligent tester. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / MISFIRE / CYL #1 (to CYL #8).

NG: REPAIR OR REPLACE IGNITION SYSTEM

OK: GO TO Next Step
INSPECT FUEL INJECTOR
HINT:

If the injectors are malfunctioning, engine misfire may occur. The misfire counter can be read with the intelligent tester. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / MISFIRE / CYL #1 (to CYL #8).

NG: REPLACE FUEL INJECTOR

OK: GO TO Next Step

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Disconnect the A50 and A51 Air Fuel Ratio (A/F) sensor connectors.
Measure the resistance of the A/F sensor.
Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
HT (1) - +B (2)	1.8 to 3.4 kΩ at 20°C (68°F)
HT (1) - AF- (4)	10 kΩ or higher

NG: REPLACE AIR FUEL RATIO SENSOR

Fig 2: Identifying Air Fuel Ratio Sensor Connector Terminals

OK: GO TO Next Step

INSPECT A/F RELAY (Marking: A/F HTR)

Remove the A/F relay from the No. 8 engine room relay block.
Measure the resistance of the A/F relay.
Standard resistance

TERMINAL CONNECTION SPECIFIED CONDITION CHART

Terminal Connection	Specified Condition
3 - 5	10 kΩ or higher
3 - 5	Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

NG: REPLACE A/F RELAY

Fig 3: Identifying A/F Relay Terminals With Circuit

OK: GO TO Next Step

CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)
1. Check harness and connector (see ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: GO TO Next Step
REPLACE AIR FUEL RATIO SENSOR
1. Replace A/F sensor (see REMOVAL ).
PERFORM CONFIRMATION DRIVING PATTERN

Fig 4: Vehicle Driving Pattern
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
2. Turn the ignition switch ON and turn the tester ON.
3. Clear DTCs (see DTC CHECK / CLEAR ).
4. Switch the ECM from normal mode to check mode using the tester (see CHECK MODE PROCEDURE ).
5. Start the engine and warm it up with all the accessories switched OFF.
6. Drive the vehicle at between 60 and 120 km/h (38 and 75 mph) and at an engine speed of between 1,400 rpm and 3,200 rpm for 3 to 5 minutes.
HINT:

If the system is still malfunctioning, the MIL will be illuminated during step (f).

NOTE: If the conditions in this test are not strictly followed, no malfunction will be detected.

CHECK WHETHER DTC OUTPUT RECURS (DTC P0171, P0172, P0174 OR P0175)

On the intelligent tester, enter the following menu: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
Read DTCs.

Result

RESULT CHART

Display (DTC Output)	Proceed to
No output	A
P0171, P0172, P0174 or P0175	B

B: GO TO step 5

A: END