Inspection Procedure

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.
Put the engine in inspection mode (See INSPECTION MODE PROCEDURE ).
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 intelligent 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 output voltages 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

FUEL INJECTION VOLUME REFERENCE

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: A/F Sensor Output Voltage Chart

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, and press the YES button and then the ENTER button followed by the F4 button.

HINT:

DTC P2A00 or P2A03 may also be set, when the air-fuel ratio is stuck rich or lean.
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.
Read freeze frame data using the intelligent tester. The ECM (Included in HV control ECU) records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00 AND/OR P2A03)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to the ON position.
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 and/or P2A03	A
P2A00 and/or P2A03 and other DTCs	B

HINT:

If any DTCs other than P2A00 or P2A03 are output, troubleshoot those DTCs first.

B: GO TO DTC CHART

A: Go to next step

READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF A/F SENSOR)

Connect the intelligent tester to the DLC3.
Put the engine in inspection mode (See INSPECTION MODE PROCEDURE ).
Start the engine.
Turn the tester ON.
Warm up the Air-Fuel Ratio (A/F) sensor at an engine speed of 2,500 rpm for 90 seconds.
On the tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / SNAPSHOT / MANUAL SNAPSHOT / USER DATA / AFS B1S1 or AFS B2S1 and ENGINE SPD.

Check the A/F sensor voltage three times, when the engine is in each of the following conditions:

While idling (check for at least 30 seconds)
At an engine speed of approximately 2,500 rpm (without any sudden changes in engine speed)

Raise the engine speed to 4,000 rpm and then quickly release the accelerator pedal so that the throttle valve is fully closed.

Standard voltage

A/F SENSOR VOLTAGE VARIATION REFERENCE

Condition	A/F Sensor Voltage Variation	Reference
(1) and (2)	Changes at approximately 3.3 V	Between 3.1 V and 3.5 V
(3)	Increases to 3.8 V or more	This occurs during engine deceleration when fuel-cut performed

HINT:

For more information, see the diagrams below.

Fig 2: A/F Sensor Output Voltage Graph (Normal/Malfunction Condition)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

If the output voltage of the A/F sensor remains at approximately 3.3 V (see Fig 2 ) under any conditions, including those above, the A/F sensor may have an open circuit, (this will also happen if the A/F sensor heater has an open circuit.)
If the output voltage of the A/F sensor remains at either approximately 3.8 V or more, or 2.8 V or less (see Fig 2 ) under any conditions, including those above, the A/F sensor may have a short circuit.
The ECM (Included in HV control ECU) stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and results in a momentary increase in the A/F sensor output voltage.
The ECM must establish a closed throttle valve position learning value to perform fuel cut. If the battery terminal has been reconnected, the vehicle must be driven over 10 mph (16 km/h) to allow the ECM to learn the closed throttle valve position.
When the vehicle is driven: The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. The vehicle translates this as 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; therefore, the current is converted into a voltage inside the ECM. Measuring the voltage at the connectors of the A/F sensor or ECM will show a constant voltage result.

NG: GO TO step 9

OK: Go to next step

PERFORM CONFIRMATION DRIVING PATTERN

CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)

Read the DTCs using the intelligent tester.

Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.

Result

RESULT REFERENCE

Display (DTC Output)	Proceed to
P2A00 and/or P2A03	A
No output	B

B: GO TO step 8

A: Go to next step

REPLACE AIR FUEL RATIO SENSOR
PERFORM CONFIRMATION DRIVING PATTERN

CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)

Read the DTCs using the intelligent tester.

Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.

Result

RESULT REFERENCE

Display (DTC Output)	Proceed to
No output	A
P2A00 and/or P2A03	B

B: REPLACE HV CONTROL ECU AND PERFORM CONFIRMATION DRIVING PATTERN

A: Go to next step

CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
NO: CHECK FOR INTERMITTENT PROBLEMS

YES: DTC CAUSED BY RUNNING OUT OF FUEL

INSPECT AIR FUEL RATIO SENSOR

Disconnect the A3 or A4 A/F sensor connector.

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

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
HA1A, HA2A(1) - +B(2)	1.8 to 3.4 Ω at 20°C (68°F)
HA1A, HA2A (1) - A1A-, A2A- (4)	10 kΩ or higher

Reconnect the A/F sensor connector.

NG: REPLACE AIR FUEL RATIO SENSOR

Fig 3: Identifying Air Fuel Ratio Sensor Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to next step

INSPECT A/F RELAY

Remove the A/F relay from the engine room R/B.

Measure A/F relay resistance.

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION

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

Reinstall the A/F relay.

NG: REPLACE A/F RELAY

Fig 4: Inspecting EFI Relay

OK: Go to next step

CHECK HARNESS AND CONNECTOR (A/F SENSOR -HV CONTROL ECU)

Disconnect the A3 and A4 A/F sensor connectors.
Turn the ignition switch to the ON position.

Measure the voltage between the +B terminal of the A/F sensor connector and body ground.

Standard voltage

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
+B (2) - Body ground	9 to 14 V

Turn the ignition switch off.
Disconnect the H33 HV control ECU connector.

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

Standard resistance (Check for open)

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
HA1A (A4-1) - HA1A (H33-4)	Below 1 Ω
A1A+ (A4-3) - A1A+ (H33-22)	Below 1 Ω
A1 A- (A4-4) - A1A- (H33-30)	Below 1 Ω
HA2A (A3-1) - HA2A (H33-3)	Below 1 Ω
A2A+ (A3-3) - A2A+ (H33-23)	Below 1 Ω
A2A- (A3-4) - A2A- (H33-31)	Below 1 Ω

Standard resistance (Check for short)

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
HA1A( A4-1) or HA1A (H33-4) - Body ground	10 kΩ or higher
A1A+ (A4-3) or A1A+ (H33-22) - Body ground	10 kΩ or higher
A1A- (A4-4) or A1A- (H33-30) - Body ground	10 kΩ or higher
HA2A (A3-1) or HA2A (H33-3) - Body ground	10 kΩ or higher
A2A+ (A3-3) or A2A+ (H33-23) - Body ground	10 kΩ or higher
A2A- (A3-4) or A2A- (H33-31) - Body ground	10 kΩ or higher

Fig 5: Identifying H33 HV Control ECU Connector Terminals

Reconnect the HV control ECU connector.
Reconnect the A/F sensor connector.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

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

OK: Go to next step
CHECK PCV HOSE
OK: PCV hose is connected correctly and is not damaged.

NG: REPAIR OR REPLACE PCV HOSE

OK: Go to next step
CHECK FUEL PRESSURE
1. Check the fuel pressure (See ON-VEHICLE INSPECTION ).
  Standard:
  
  304 to 343 kPa (3.1 to 3.5 kgf/cm ² , 44.1 to 49.7 psi)
NG: REPAIR OR REPLACE FUEL SYSTEM

OK: Go to next step
INSPECT FUEL INJECTOR
1. Check the injector injection (See INSPECTION ).
  Standard:
  
  13 cm ³ (0.8 cu in.) or less
NG: REPLACE FUEL INJECTOR ASSEMBLY

OK: Go to next step
REPLACE AIR FUEL RATIO SENSOR
PERFORM CONFIRMATION DRIVING PATTERN

CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)

Read the DTCs using the intelligent tester.

Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.

Result

RESULT REFERENCE

Display (DTC Output)	Proceed to
No output	A
P2A00 and/or P2A03	B

B: REPLACE HV CONTROL ECU

A: Go to next step

CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
NO: CHECK FOR INTERMITTENT PROBLEMS

YES: DTC CAUSED BY RUNNING OUT OF FUEL