Inspection Procedure

HINT:

Malfunctioning areas can be found by performing the ACTIVE TEST / A/F CONTROL operation. The A/F CONTROL operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble area are malfunctioning or not.

Perform the ACTIVE TEST A/F CONTROL operation.
HINT:

The A/F CONTROL operation lowers the injection volume 12.5% or increases the injection volume 25%.
1. Connect the intelligent tester to the DLC3.
2. Turn the power switch ON (IG).
3. Put the engine in inspection mode (see SFI SYSTEM ).
4. Warm up the engine by running the engine at 2,500 rpm, depressing the accelerator pedal more than 60% for approximately 90 seconds.
5. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
6. Perform the A/F CONTROL operation with the engine in an idle condition (press the right or left button).

Result:

A/F sensor reacts in accordance with increase and decrease of injection volume:

+25% → rich output: Less than 3.0 V

-12.5% → lean output: More than 3.35 V

Heated oxygen sensor reacts in accordance with increase and decrease of injection volume:

+25% → rich output: More than 0.55 V

-12.5% → lean output: Less than 0.4 V

NOTE: The A/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay at maximum.

Fig 1: A/F Sensor - Blinking Pattern

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The following A/F CONTROL procedure enables the technician to check and graph the voltage output of both A/F sensor and heated oxygen sensor.

To display the graph, enter ACTIVE TEST/A/F CONTROL/USER DATA, select "AFS B1S1 and O2S B1S2" by pressing the "YES" button followed by the "ENTER" button and then the "F4" button.

HINT:

DTC P2A00 may be also detected, when the air-fuel ratio stays RICH or LEAN.
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
A high A/F sensor voltage could be caused by a RICH air-fuel mixture. Check the conditions that would cause the engine to run with the RICH air-fuel mixture.
A low A/F sensor voltage could be caused by a LEAN air-fuel mixture. Check the conditions that would cause the engine to run with the LEAN air-fuel mixture.

CHECK OTHER DTC OUTPUT (IN ADDITION TO A/F SENSOR DTC)

Connect the intelligent tester to the DLC3.
Turn the power switch ON (IG).
Turn the tester ON.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

Read the DTCs.

Result

RESULT REFERENCE

Display (DTC Output)	Proceed to
P2A00	A
P2A00 and other DTCs	B

HINT:

If any other code besides P2A00 are output, perform troubleshooting for those DTCs first.

B: Go to DTC CHART

A: Go to Next Step

READ VALUE OF INTELLIGENT TESTER (OUTPUT VOLTAGE OF A/F SENSOR)
1. Connect the intelligent tester to the DLC 3.
2. Put the engine in inspection mode (see SFI SYSTEM ).
3. Warm up the A/F sensors (bank 1 sensor 1) by running the engine at 2,500 rpm with the accelerator pedal depressed more than 60% for approximately 90 seconds.
4. Read A/F sensor voltage output on the intelligent tester.
5. Enter the following menus: ENHANCED OBD II / SNAPSHOT / MANUAL SNAPSHOT / USER DATA.
6. Select "AFS B1 S1/ENGINE SPD" and press button "YES".
7. Monitor the A/F sensor voltage carefully.
8. Check the A/F sensor voltage output under the following conditions:
  1. Put the engine in inspection mode and allow the engine to idle for 30 seconds.
  2. Put the engine in inspection mode and running the engine at 2,500 rpm with the accelerator pedal depressed more than 60% (where engine RPM is not suddenly changed).
  3. Deactivate the inspection mode and drive the vehicle with the shift position in "B" range.
  4. Accelerate the vehicle to 70 km/h (44 mph) and quickly release the accelerator pedal so that the throttle valve is fully closed.
  CAUTION:
  - Strictly observe of posted speed limits, traffic laws, and road conditions when performing these drive patterns.
  - Do not drive the vehicle without deactivating inspection mode, otherwise damaging the transaxle may result.
  OK: Condition (1) and (2)
  Voltage changes in the vicinity of 3.3 V (between approximately 3.1 to 3.5 V) as shown in the illustration. Condition (4)
  A/F sensor voltage increases to 3.8 V or more during engine deceleration (when fuel cut) as shown in the illustration.
  Fig 2: Engine Speed Graph
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  HINT:
  - Whenever the output voltage of the A/F sensor remains at approximately 3.3 V (see diagram Malfunction Condition) under any condition as well as the above conditions, the A/ F sensor may have an open-circuit. (This will happen also when the A/F sensor heater has an open-circuit.)
  - Whenever the output voltage of the A/F sensor remains at a certain value of approximately 3.8 V or more, or 2.8 V or less (see diagram Malfunction Condition) under any condition as well as the above conditions, the A/F sensor may have a short-circuit.
  - The ECM will stop fuel injection (fuel cut) during engine deceleration. This will cause a LEAN condition and should result in a momentary increase in A/F sensor voltage output.
  - The ECM must establish a closed throttle position learned value to perform fuel cut. If the battery terminal was reconnected, the vehicle must be driven over 10 mph to allow the ECM to learn the closed throttle position.
  - When the vehicle is driven:
    The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. For the vehicle, this translates to a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The A/ F sensor is functioning normally.
  - The A/F sensor is a current output element, and therefore the current is converted into voltage inside the ECM. If measuring voltage at connectors of A/F sensor or ECM, you will observe a constant voltage.
OK: Go to step 14

NG: Go to Next Step

INSPECT AIR FUEL RATIO SENSOR (RESISTANCE OF A/F SENSOR HEATER)

Disconnect the A5 A/F sensor connector.

Measure the resistance between the terminals of the A/F sensor.

Standard resistance

TESTER CONNECTION

Tester Connection	Resistance
1 (HT) - 2 (+B)	1.8 to 3.4Ω at 20°C(68°F)

Reconnect the A/F sensor connector.

NG: REPLACE AIR FUEL RATIO SENSOR

Fig 3: Identifying A5 A/F Sensor Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to Next Step

INSPECT INTEGRATION RELAY (EFI M RELAY)

Remove the integration relay from the engine room relay block.

Inspect the EFI M relay.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
3K-1 - 3I-8	10 kΩ or higher
3K-1 - 3I-8	Below 1 Ω (Apply battery voltage to terminals 3I-6 and 3I-7)

Reinstall the integration relay.

NG: REPLACE INTEGRATION RELAY

Fig 4: Identifying Integration Relay From Engine Room Relay Block

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to Next Step

CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)

Disconnect the A5 A/F sensor connector.

Fig 5: Identifying A5 A/F Sensor Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the E5 ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard resistance (Check for open)

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
A5-3 (AF+) - E5-23 (A1A+)	Below 1 Ω
A5-4 (AF-) - E5-22 (A1A-)	Below 1 Ω
A5-1 (HT) - E5-7 (HA1A)	Below 1 Ω

Fig 6: Disconnecting E5 ECM Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard resistance (Check for short)

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
A5-3 (AF+) or E5-23 (A1A+) - Body ground	10 kΩ or higher
A5-4 (AF-) or E5-22 (A1A-) - Body ground	10 kΩ or higher
A5-1 (HT) or E5-7 (HA1A) - Body ground	10 kΩ or higher

Reconnect the A/F sensor connector.
Reconnect the ECM connector.

Fig 7: Oxygen (A/F) Sensor - Circuit Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to Next Step

CHECK AIR INDUCTION SYSTEM
1. Check for vacuum leaks in the air induction system.
  OK: There is no leakage in the air induction system.
NG: REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK: Go to Next Step
CHECK CONNECTION OF PCV HOSE
OK: PCV hose is connected correctly and PCV hose has no damage.

NG: REPAIR OR REPLACE PCV HOSE

OK: Go to Next Step
CHECK FUEL PRESSURE
OK: Fuel pressure: 304 to 343 kPa (3.1 to 3.5 kgf/cm ² , 44 to 50 psi)

NG: REPAIR OR REPLACE FUEL SYSTEM

OK: Go to Next Step
INSPECT FUEL INJECTOR ASSEMBLY
1. Check the injector injection (high or low fuel injection quantity or poor injection pattern).
  OK: Injection volume: 36 to 46 cm ³ (2.1 to 2.8 cu in.) per 15 seconds.
NG: REPLACE FUEL INJECTOR ASSEMBLY

OK: Go to Next Step
REPLACE AIR FUEL RATIO SENSOR
PERFORM CONFIRMATION DRIVING PATTERN
HINT:

Clear all DTCs prior to performing the confirmation driving pattern (see WIRING DIAGRAM ).

READ OUTPUT DTC (SEE IF A/F SENSOR DTC IS OUTPUT AGAIN)

Connect the intelligent tester to the DLC3.
Turn the power switch ON (IG).
Turn the tester ON.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

Read the DTCs.

Result

RESULT REFERENCE

Display (DTC Output)	Proceed to
No output	A
P2A00 is output again	B

B: REPLACE ECM AND PERFORM CONFIRMATION DRIVING PATTERN

CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
OK: The vehicle has run out of fuel in the past.

NO : CHECK FOR INTERMITTENT PROBLEMS

YES : DTC IS CAUSED BY RUNNING OUT OF FUEL
PERFORM CONFIRMATION DRIVING PATTERN
HINT:

Clear all DTCs prior to performing the confirmation driving pattern (see WIRING DIAGRAM ).

GO: Go to Next Step

READ OUTPUT DTC (SEE IF A/F SENSOR DTC IS OUTPUT AGAIN)

Connect the intelligent tester to the DLC3.
Turn the power switch ON (IG).
Turn the tester ON.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

Read the DTCs.

Result

RESULT REFERENCE

Display (DTC Output)	Proceed to
P2A00	A
No output	B

B: Go to step f

A: Go to Next Step

REPLACE AIR FUEL RATIO SENSOR
GO: Go to Next Step
PERFORM CONFIRMATION DRIVING PATTERN
HINT:

Clear all DTCs prior to performing the confirmation driving pattern (see WIRING DIAGRAM ).

GO: Go to Next Step

READ OUTPUT DTC (SEE IF A/F SENSOR DTC IS OUTPUT AGAIN)

Connect the intelligent tester to the DLC3.
Turn the power switch ON (IG).
Turn the tester ON.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

Read the DTCs.

Result

RESULT REFERENCE

Display (DTC Output)	Proceed to
No output	A
P2A00	B

B: REPLACE ECM AND PERFORM CONFIRMATION DRIVING PATTERN

A: Go to Next Step

CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
OK: The vehicle has run out of fuel in the past.

NO : CHECK FOR INTERMITTENT PROBLEMS

YES : DTC IS CAUSED BY RUNNING OUT OF FUEL